Steak fajitas are a staple Tex-Mex meal served taco style with thinly sliced steak strips loaded with tender-crisp veggies that are stuffed inside an ever-inviting corn tortilla.
Cut flank steak against the grain into thin strips. Place meat into a gallon sized plastic bag and pour in the marinade. Seal the bag and allow to marinate at room temperature for one hour.
Cut bell peppers and onion into thin strips.
Heat olive oil in a cast iron skillet over medium-high heat until shimmering.
Add bell pepper and onion strips and cook, stirring occasionally, until tender crisp, about 2-3 minutes.
Move all the vegetables to one side of the pan. Using tongs or your gloved hand, remove beef from marinade and add it to the empty side of the pan. Cook, stirring occasionally for 1-2 minutes. Discard leftover marinade.TIP - We like our meat to be juicy, so we add the meat to the pan right out of the marinade. If you prefer less pan juices, drain the marinated meat first and gently pat dry with paper towels.
Stir vegetables and beef together, cooking for an additional 2-3 minutes. Turn off heat and set pan aside.
CAUTION: the next step requires an open flame. If you prefer, you can also heat the tortillas in a dry skillet but the flame gives you those nice char marks.Toast tortillas over open flame on your stove, turning with tongs. Do not leave the tortillas alone and they will need to be turned fairly quickly.
Each side only needs about 5-10 seconds on the burner.
Notes
Cut the flank steak thinly against the grain. Slicing against the grain means to cut against (perpendicular) the fibers that run through the meat. This will help tenderize and make it easier to chew.
Flank steak is among the most popular choice of beef for fajitas. You can also use skirt steak, though skirt steak is a bit tougher than flank so you may want to cook it for less time to avoid overly fibrous beef strips. Both cuts are lean and work really well with marinades which help tenderize the meat.
Store the leftover beef and veggies separate from the tortillas (so they don't get soggy), in an air-tight container kept in the refrigerator for 3-4 days.
To reheat, warm the veggies and beef in a skillet over medium to low heat until warmed through, it should only take a few minutes. Alternatively reheat in a 250F oven for around 10 minutes. You don't want to end up overcooking the beef by reheating it at too high of temperatures which will cause it to be tough and chewy.
You can freeze the leftover filling, separate from the tortillas, for up to 3 months. Place the cooled beef and veggies in a sealed freezer bag or airtight container. Thaw in the refrigerator overnight and reheat on the stovetop.