This delicious Marinated Flank Steak is a quick, low carb dish bursting with flavor! Easy keto meal prep recipe for fajitas, tacos, breakfast burritos, and more!
Marinated Flank Steak
Flank steak is a delicious lean cut of beef, but it can sometimes be a bit tough. Marinating this cut helps bring out the tender beauty of this steak, turning a fairly inexpensive cut into a meal fit for company! It also packs a big punch of flavor, making it an excellent protein to add to a variety of meals–perfect for meal prepping!
This recipe requires only 12 minutes of cook time, but you’ll want to be patient with the marinade. Luckily, it can do its job while you are sleeping or at work!
Flank Steak Marinade Ingredients
As always, here’s a quick overview of what you’ll need. Scroll down to the printable recipe card for specific measurements and instructions!
- Flank steak : I went with a 1.5 pound cut
- Steak marinade : I prefer Allegro, but you can use your favorite
- Olive oil
- Lime juice
- Garlic : minced
- Jalapeño : seeded and chopped
- Red onion, chopped
- Fajita seasoning*
How to Marinade Flank Steak for Tenderness
Marinating does two things: It adds tons of flavor and it tenderizes meat. When using a lean cut like flank steak, you can get a much more tender, appetizing dish if you can marinate it for several hours in a mixture that can break down the tissue in the meat! Marinades may use an acid (like vinegar or citrus juice) or enzymes (most naturally produced in fruits like kiwis and papayas).
For this marinade, I used lime juice in the mixture to help turn the flank cut into a melt-in-your-mouth steak on a budget. I knew I wanted to embed a Mexican/fajita flavor, and the lime does double duty by tenderizing and complementing this flavor profile!
How long should I marinate flank steak?
If you’re in a rush and are more concerned about adding flavor vs. tenderness, you could marinate for as little as 30 minutes! Granted, this isn’t enough time for the marinade to break down the tissue or penetrate deep into the meat, but it will absolutely give a great flavor.
For tenderizing meat, it’s important that you have your steak in the marinade for at least 2 hours. 12 hours is considered ideal, but up to 24 hours will be fine. You don’t want to marinate longer than that as the acid will break down tissue too much, changing the texture of the steak.
How to Cook Marinated Flank Steak
This is incredibly easy and quick enough for a weeknight! First, start by combining your steak marinade, olive oil, lime juice, garlic, red onion, and jalapenos in a bag or large container, then add your flank steak. Make sure your steak is well covered (if it’s not covered, just be sure to flip occasionally so that every bit can soak up some of the marinade. Marinate anywhere from 30 minutes to 24 hours (the longer you marinate, the more tender and flavorful it’ll be).
**Tip: If you are meal prepping or know that you will have leftovers, reserve a portion of the marinade (before placing steak in it) or make a double batch for reheating. It’s much easier to have juicy, leftover steak if you reheat it in a few tablespoons of the marinade! The marinade alone can be stored in a jar in the fridge at least 1 week.**
When ready to cook, heat a skillet, griddle, or grill to high heat, about 400 degrees F. Sprinkle the fajita seasoning on top of the steak (the least fatty side is the top), then place the steak fatty-side down. Cook for approximately 6 minutes, then flip and cook another 5-6 minutes. Use a thermometer to determine when the steak has reached your ideal temperature. Allow steak to rest before serving.
How long should I cook flank steak?
The cook time is determined by your preferred cut. The most reliable way to monitor your steak is to use a meat thermometer to ensure it has reached your preferred level of doneness. After you remove your steak from the skillet or grill, remember that the temperature will rise a few degrees while resting. Here’s a simple guide to temperatures and doneness:
- Medium Rare: 135 degrees F or 57 degrees C
- Medium: 145 degrees F or 63 degrees C
- Medium Well: 150 degrees F or 66 degrees C
- Well: 160 degrees F or 71 degrees C
Do you have to let a steak rest before cutting?
Yes, allowing a steak to rest is absolutely necessary for the perfect juicy steak! Not to get too science-y, but you have to remember that a steak is just a bunch of juicy little cells. These cells contract when warmed up, leading them to migrate to the coldest part (the center) while cooking.
If you cut into a steak right off the grill before allowing it to rest, all these juicy little cells will simply spill out onto your plate, leading the edges of the steak to be dry and lacking in flavor. However, if you allow the steak to rest, the temperature momentarily goes up (as it’s finishing cooking), then starts cooling off.
As the steak begins to cool, the juicy cells can spread out again and settle throughout the entire steak, not just the middle. A well-cooked and rested steak is juicy from end to end with more juice inside the steak than on your plate!
How do you cut a flank steak?
For the most tender bites of deliciously marinated flank steak, make sure to cut then slices diagonally against the grain. This helps break down any remaining tough strings of fiber, giving you juicy, easy-to-chew bites of heaven! It’s easiest to find the grain when the steak is raw–It’s the white lines you see running down the front and back of the steak.
If you were cutting WITH the grain, you would slice in the same direction as the lines. If you were cutting AGAINST the grain, you would slice perpendicular to the lines (at a 90 degree angle). We’re cutting DIAGONNALLY AGAINST, so we’re cutting across the lines more at a 45 degree angle.
How to store cooked steak
Steak can quickly become overcooked and dry when reheating, so take care to store it the right way. If you are meal prepping your steak for other recipes and know that you will be reheating it later, it’s best to reserve some of the marinade (BEFORE the raw meat goes in it) or make a double batch to store in the fridge. When reheating, you’ll pour 2-3 tablespoons of this marinade on the steak, helping it stay juicy and delicious while coming to temperature.
If you cooked your flank steak ahead of time and are storing it in the fridge unsliced, it’s best to wrap it tightly in freezer paper (that thick paper with a waxy side), then store in a bag. Push out as much air as possible, and this storage method will help keep all that delicious juice in the steak!
When storing sliced flank steak, store the strips in a bag with a few tablespoons of reserved marinade and push as much air out as possible. Steak will stay fresh in the fridge up to 3-4 days. You can eat it cold (amazing in lunch wraps or salads) or warm (perfect for tacos or to add to spaghetti squash).
How to reheat steak without overcooking
To reheat the full, unsliced steak, you can pour reserved marinade over it and warm it covered in the oven (350 degrees F) until it reaches about 120-125 degrees F. To reheat sliced steak (whether sliced before or after refrigerating), you can use the same oven method (won’t take as long as a full steak) or microwave in 20-second increments at 50% power until warm. If you like crispy bits, you can toss into a hot skillet.
What should I serve with flank steak?
There are SO many options with this versatile marinated flank steak! You could create a taco bar and serve this with Pollo con Queso, Cilantro Lime Shrimp, and Carnitas for an easy dinner option everyone will love.
These Zucchini Keto Tortillas are both low carb and keto–They would make delicious tacos! Serve with Cilantro Lime Rice and Roasted Tomatillo Salsa for a flavor-packed, low carb dinner! This Avocado Bacon Dip would be a fantastic side or appetizer with chips (if low carb, just cut up some Mission Carb Balance tortillas and toast them for easy keto-friendly chips).
Because this can be used in so many ways, it makes a fantastic beef meal prep recipe–You could use this beef for fajitas, tacos, burritos, make taco salad, or use cauliflower rice for a keto Mexican bowl! Check out these Keto Meal Prep Ideas for more ways to use this beef!
More Keto Mexican Recipes:
- 1.5 pound flank steak
- 1/2 cup steak marinade (I love Allegro)
- 2 tablespoons olive oil
- 2 tablespoons lime juice
- 1 tablespoon minced garlic
- 1/4 cup jalapeño, seeded and chopped
- 1/4 cup red onion, chopped
- 2 tablespoons fajita seasoning* (see note below)
- Combine the steak marinade, olive oil, lime juice, garlic, red onion, and jalapenos. Pour the marinade over the steak and marinade at least 30 minutes (the longer the better).
- When ready to cook, heat a skillet, griddle or grill to high heat (approximately 400 degrees).
- Sprinkle the fajita seasoning on the top (least fatty side) of the steak. Place the steak fatty side down and cook for approximately 6 minutes. Flip and cook an additional 5-6 minutes.**
**Use a meat thermometer to determine when to remove your steak follow this as a guide:
Medium Rare: 135 degrees F or 57 degrees C
Medium: 145 degrees F or 63 degrees C
Medium Well: 150 degrees F or 66 degrees C
Well: 160 degrees F or 71 degrees C
I use a fajita seasoning blend for this recipe, if you prefer, you can use taco seasoning. The Fajita seasoning blend I reccomend is listed below. You will need 2 tablespoons of this blend for the marinated flank steak.
Fajita seasoning blend
- 1/4 cup chili powder
- 2 tablespoons paprika
- 1 tablespoon cumin
- 1 tablespoon onion powder
- 1 tablespoon garlic powder
- 2 teaspoons oregano
- 1 teaspoon salt
- 1 teaspoon pepper
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Nutrition Information:Yield: 6 Serving Size: 3 ounces
Amount Per Serving: Calories: 211Total Fat: 11.7gCholesterol: 67mgSodium: 192mgCarbohydrates: 1.6gNet Carbohydrates: 1.5gFiber: 0.1gSugar: 0.4gProtein: 24g