Trim the fat off the skirt steak if there is any. Pound out the flank steak with a meat tenderizer. Squeeze lime juice over the flank steak.
Prepare the marinade by whisking all the ingredients together. Put skirt steak in marinade for 2 to 24 hours, and refrigerate.
Turn the stove on to medium-high and place a cast-iron skillet on top.
Once it is hot, pull skirt steak out of the marinade, and put in skillet. Cook for one minute, then flip it over and cook for an additional minute. Transfer meat to a plate.
Put olive oil into the skillet and add onions and peppers then cook for 10 minutes.
Pour accumulated juices from the meat plate over the veggies and toss to coat.
Slice meat against the grain, then place it back into the skillet, and toss to combine.
Serve with fresh flour tortillas, sour cream, guacamole, pico de gallo, and cheese!