Flank Steak Fajitas

Four fajitas with flank steak, peppers, and shallots on an sheet pan next to a bowl of cilantro.

5 from 6 votes

These flank steak fajitas are quickly marinated and then pan-seared for a flavorful recipe that's great for a high protein weeknight meal or meal prep.

Prep Time20

Cook Time10

Total Time30

Course: Dinner

Cuisine: American, Mexican

Diet: Gluten Free, Low Lactose, Low Salt

Servings: people

Author: Alicia

Ingredients

Marinade

1 pound flank steak sliced thinly (about 1/2 inch) against the grain, about 2-3 inch long pieces
1 tablespoon cooking oil avocado oil or high heat olive oil recommended
2 garlic cloves, minced
1 tablespoon white vinegar
2 tablespoons tart cherry juice or lime juice
1 teaspoon ground cumin
1/2 teaspoon smoked paprika
1 teaspoon kosher salt

Steak Fajitas

1½ cups yellow onion or shallots about 4 large shallots or 1 large yellow onion, sliced into strips
2 bell peppers sliced into strips
8 small flour tortillas
2 tablespoons cooking oil (avocado, high heat olive oil or vegetable oil)
kosher salt and black pepper to taste

US Customary - Metric

Instructions

In a large ziplock bag or bowl, combine the flank steak, oil, garlic, vinegar, juice, cumin, paprika, and 1 teaspoon kosher salt. Allow the steak to marinate for at least 20 minutes, up to overnight. If only marinating 20 minutes, leave out at room temperature.
Meanwhile, heat 1 tablespoon of oil in a cast iron or non-stick pan over medium high heat. Add bell pepper and shallots, not touching it for at least 1 minute to develop a nice char on one side. Then stir around the pan, cooking until softened. About 4-5 minutes total. Add kosher salt and black pepper to taste. Remove the shallots and bell peppers from the pan and put in an oven safe dish. You can add to the oven with the tortillas to keep warm, or just cover and set aside.
Add one more tablespoon of oil to the same pan and place the sliced steak evenly, leaving space between pieces. Do not touch the steak for at least 2 minutes to get a nice char on one side, then stir to evenly brown on the other side - 4-5 minutes total.
Place cooked flank steak in tortillas with bell peppers and onions or shallots. Top with any favorite toppings like salsa cheese, cilantro, sour cream, or avocado.
To heat the tortillas - If you have a gas stove, place the tortilla on top of the grate over the open flame for about 30 seconds, watching carefully so there is a slight char, but it doesn't fully burn. When softened, flip and do the same on the opposite side. Oven method - Wrap tortillas completely in aluminum foil. Preheat oven to 350℉/177℃ and place the wrapped tortillas and shallot/pepper mixture in the oven to keep warm.

Notes

On tart cherry juice - It sounds weird but makes a fantastic marinade for flank steak that's both tart and rich at the same time. But if you don't want to purchase a whole bottle for this recipe, this can be substituted for lime juice, coconut aminos, or soy sauce. If using lime juice, you can omit the added white vinegar. But if using the others, it needs the acidity.
Kosher salt - I use Diamond kosher salt, which is a little less salty than Morton's. Take note of this as you season the fajitas, as you may want to cut back to 1/2 teaspoon in the marinade. You can always add more salt if desired.
Cutting the flank steak - It's very important to slice the flank steak against the grain, which means to cut it in the opposite direction of where the lines run, not parallel to them. This will provide more tender steak vs. one that's tough to chew.
Marinade - You can marinate the steak as little as 20 minutes, up to 24 hours. Beyond that, the steak may begin to get mushy.
HYH diet - See the post for brand recs. Use shallots instead of onions and either the tart cherry juice or coconut aminos. Do not use sour cream or avocado.

Nutrition