Slice the skirt steak then cut the slices in half lengthwise . Put a frying pan on the stove a medium high with a tbsp. of olive oil. Slice the onions and the peppers. Chop the garlic and put the veggies and the meat in the pan. Mix it up and mix it again every minute or so until it is done. Traditionally it is cooked until it just begins to get crispy, but, you cook it as much as you want.
Put the biggest frying pan that you have on the stove at medium heat. put as many tortillas as will fit on to warm up. Spoon some of the meat and veggies on each tortilla. Spread some Pico de Gallo on top then spread some shreaded cheese on top. Put another tortilla on it and heat them up for about 3 minutes a side, or crispier if you like.
Serve it up! With a dab of sour cream, Pico de Gallo and guacamole. Oh yeah. Don't forget some good Mexican beer and/or Tequila.