Keto Steak Marinara
Published August 31, 2020 • Updated March 2, 2026
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I turn leftover steak into this steak marinara freezer meal every time we have extra from dinner. Slice, bag, freeze, and cook it in the Instant Pot or on the stovetop whenever you need a fast keto dinner.
Steak marinara sauce recipe
I started making this steak marinara after a night where I had half a pound of leftover ribeye and zero motivation to cook something new. Five minutes of slicing and bagging, and I had a freezer meal ready for the following week. That was three years ago, and I still make a batch every time we have steak for dinner.
The concept is dead simple. Take your leftover steak (any cut works, though I get the best results with flank and sirloin), slice it thin against the grain, and toss it into a freezer bag with marinara, diced tomatoes, spinach, and Italian seasoning. Seal it flat, freeze it, and you have a keto dinner that goes from freezer to table in under 30 minutes. I keep two or three bags in rotation at all times.
What sets this apart from just reheating leftover steak is the sauce. The marinara breaks down into the meat during pressure cooking, and every slice absorbs that rich, tangy tomato flavor. The spinach wilts to practically nothing, which is exactly why I load the bag with two full cups. You get the nutrition without the bulk. If you like my Instant Pot Swiss Steak, you will love how this comes together the same way.
I have made this both from thawed and from frozen. Thawed is faster (7 minutes on high pressure), but frozen works if you add 1/4 cup of water to the liner so nothing scorches. I learned that the hard way. No pressure cooker? The stovetop method is just as good. Thaw the bag overnight, dump it in a skillet, and heat until the sauce is bubbling. It is the same kind of weeknight dinner as my Keto Philly Cheesesteak, just with an Italian spin.
One thing I picked up from a reader: portion into single-serving bags before you freeze. I used to freeze one giant batch and then hack at a frozen block trying to get one plate out. Smaller bags mean you thaw only what you need for one meal. Same cook time, zero waste.
Pour it over cauliflower rice, hearts of palm noodles, or low carb pasta and it is a full dinner. My husband does not even ask what is in it anymore. He just eats it. If you are looking for more Instant Pot meals like this, my Keto Hamburger Helper is another one I keep in the regular rotation.
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Ingredients
1 lb sliced pre-cooked steak -
1/2 cup onion, diced
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2 cups fresh baby spinach leaves
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2 teaspoons Italian seasoning
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1 teaspoon salt
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1/2 teaspoon pepper
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2 teaspoons garlic paste or 2 cloves garlic, minced
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1 cup low-carb marinara sauce or tomato sauce
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1 cup canned diced tomatoes
Step by Step Instructions
Step by Step Instructions
Add ingredients to freezer bag
Add all the ingredients to a gallon sized freezer bag.
Freeze
Press all the air out of the bag and seal. Store flat in the freezer until ready to cook.
Pressure cook
To prepare, thaw in the refrigerator the night before. Add all ingredients to the liner of an instant pot. Attach the lid and set the vent to seal. Pressure cook on high for 7 minutes. Release pressure by turning the knob to venting. If cooking from frozen, add 1/4 cup of water to the liner of the instant pot along with the ingredients to prevent the contents from burning.
Serve
Pour steak marinara over low-carb noodles or cauliflower rice.
Nutrition disclaimer
The nutrition information provided is an estimate and is for informational purposes only. I am a Doctor of Pharmacy (Pharm.D.); however, this content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician or other qualified health provider before making any lifestyle changes or beginning a new nutrition program.
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Get My Macros + Recipes →Frequently Asked Questions
Can I use raw steak instead of leftover steak?
I have done it both ways. With raw steak, you need to increase the Instant Pot time to about 12-15 minutes on high pressure depending on thickness. I slice it thin (about 1/4 inch) so it cooks evenly. The texture is slightly different since raw steak firms up more during pressure cooking, but the flavor is just as good. My preference is still leftover steak because the pre-cooking gives it a better chew in the finished dish.
Should I portion into individual bags before freezing?
This is something I started doing after a reader mentioned it, and I will never go back to the big-batch method. I portion everything into single-serving freezer bags before they go in the freezer. That way I only thaw what I need for one dinner. Same cook time, no waste, and no hacking at a frozen block with a knife.
Does the spinach disappear into the sauce?
Pretty much, yes. I load in two full cups of fresh baby spinach and it wilts down to almost nothing during cooking. That is actually why I go heavy on it. You get the nutrition without changing the texture or flavor of the dish. If you want even more greens, you could easily add an extra cup and not notice a difference.
What cut of steak works best for this recipe?
I have tested this with ribeye, flank, sirloin, and New York strip. They all work. Flank is my top pick because the thinner slices soak up the marinara better during pressure cooking. A reader confirmed the same thing with leftover flank from taco night. Ribeye is richer but can get a little soft. Sirloin is a solid middle ground if you want something leaner.
Can I add mushrooms or other vegetables?
I have thrown in sliced mushrooms and they basically vanish into the sauce, which is a great trick if someone in your house claims they do not like mushrooms. A reader added them to stretch the recipe to five servings without changing the Instant Pot cook time at all. I would keep additions to things that cook quickly at the same rate: bell peppers, zucchini, or diced onion work well.
How long does this keep in the freezer?
I have pulled bags out after two to three months and they tasted exactly the same as week-old ones. Seal the bag flat with as much air pressed out as possible and it stores well. In the fridge, my leftovers keep for three to four days in an airtight container.
What can I use instead of store-bought marinara sauce?
I keep Rao's on hand most of the time, but when I run out I make a simple sauce from canned crushed tomatoes, dried Italian herbs, a little garlic, and salt. It takes about five minutes on the stove. The key is checking the sugar content on whatever brand you grab. Some jarred sauces sneak in 8-10 grams of sugar per serving, and that adds up fast on keto.
I'm normally the one rationing freezer meals to make them last, but my husband started pulling these out himself. Now I just make more. The steak doesn't taste like leftovers once the sauce works through it, more like it was supposed to cook that way.
Usually I'd say freezer dump meals trade quality for convenience, but the steak here absorbs the marinara and comes out more tender than it went in. Most leftover-steak methods can't pull that off. Runs mild as written, though. Red pepper flakes from the start would help.
Drain the diced tomatoes before they go in the bag. First time the sauce ran thin and that was why. Added a tablespoon of tomato paste on the second batch and it was totally different, thick and red, coating every piece of steak. Worth the fix.
Draining is the right call. I started doing the same after my first batch came out watery, and that tablespoon of tomato paste is what gets the sauce to actually coat. Smart fix, Camila.
We've been doing a big freezer meal push this summer (anything to avoid turning the oven on) and this steak marinara is going in the rotation. Planning to make four or five bags at once this weekend. When I thaw each one and cook it in the Instant Pot, does the pressure cook time stay the same per bag, or does it change depending on how thawed each bag is? I've had other IP recipes get finicky when I batch-prepped them.
The sauce gets this deep tomato flavor once the steak releases its juices into it, which I didn't fully appreciate until I brought a batch to a friend's birthday dinner and two people asked what I'd added to the marinara. Nothing extra, it turns out. Plated over zucchini noodles with some parmesan, it looked like more work than dumping a freezer bag into the Instant Pot. Keeping a few bags stocked at all times now.
The steak does all of it once the juices go in. Took me a while to stop adding things and just trust that. Zucchini noodles with some parmesan on top and nobody at the table thinks freezer meal.
4.5 net carbs. On batch three already.
Batch three. Individual bags made that possible.
First freezer dump bag I've actually committed to, and I went stovetop instead of Instant Pot. Pulled it from the fridge after an overnight thaw, got the garlic paste blooming in oil first before adding everything else. Used Primal Kitchen marinara because that was open. Had real doubt about whether pre-cooked steak would hold up or go rubbery, but it came out tender. Actually shocked me. Spinach looked like way too much going into the bag but folded down to almost nothing once it hit the pan. Two more bags in the freezer already.
Garlic paste bloomed in oil first is the right call, the sauce picks up that depth before anything else dilutes it. Primal Kitchen is solid for this. Two bags in the freezer means dinner is actually handled.
Those two bags were gone in like three days. Going much bigger next time.
Third time making this and I think I finally got the onions right (was rushing them before and not realizing it changed anything). The sauce is just different when they've had more time, less sharp somehow. Made me rethink what I'd been doing wrong the first two batches. Still not totally sure about my garlic paste ratio because I kind of eyeball it, but I keep coming back to this one.
Slow onions do more than they look. That sharpness cooks right out and the whole sauce gets sweeter for it.
Used Rao's arrabbiata instead of regular marinara and now I'm planning dinners around this instead of just throwing it together from leftovers.
Arrabbiata in this makes sense. The heat cuts through the fat and you end up with something that actually stands on its own instead of tasting like leftovers.
Swapped the spinach for mushrooms because I was completely out, and they basically melted into the marinara and made everything richer somehow. Ate it straight from the Instant Pot insert, didn't regret a thing. Didn't even bother with noodles. Making this again Friday with double the garlic.
Mushrooms do that every time. Disappear but add depth to the sauce. Double garlic on Friday is a good plan.
Made this with leftover ribeye Sunday. My son treats spinach like a personal enemy and he cleaned his bowl. Says everything.
Ribeye soaks up the marinara so well. And the spinach. I load in two full cups because it wilts down to almost nothing. He never noticed.
We do big steaks on the weekend pretty regularly, so there's almost always extra. Started using the leftovers for this a few months back and now I actually look forward to having extra on purpose. The Instant Pot version is what sold me. Spinach wilts right into the sauce and it comes together like it's been simmering for hours, not 10 minutes from frozen. Cauliflower rice underneath and it doesn't feel like a leftover meal at all.
The Instant Pot from frozen version is the one I make most. That 10 minutes feels impossible but it works. Cauliflower rice underneath is what I do too.
My mom used to throw together something close to this on busy weeknights, over regular pasta with jarred sauce. I made this version last week with leftover ribeye from Sunday and when it started warming up in the Instant Pot, the smell hit me out of nowhere. I wasn't expecting to get sentimental over a freezer meal. The marinara with the spinach and garlic paste tastes like something I grew up eating. Going to keep this in the rotation.
Ribeye fat does something to the marinara that flank doesn't. Sauce comes out richer. And the garlic paste smell when that lid pops (yeah, every time).
I've never done a freezer meal before, and I picked this one because I had leftover steak and zero plan for it. Threw everything in the bag Sunday night, cooked it Thursday in the Instant Pot, and the steak came out freaking tender. Doing this every single time we grill now.
Leftover grill steak was kind of the reason I made this in the first place. Thursday dinner sorted.
If you press the bag completely flat before freezing it stacks perfectly in the back of your freezer, which sounds obvious but I never figured that out until this recipe. Pulled one out last week when I had nothing planned and it was on the table in like 20 minutes.
20 minutes on a nothing-planned night is the whole reason I make this in batches. And yeah, the flat bag thing took me embarrassingly long to figure out.