You can use skirt or flank steak. Rub the outside of the meat with Kosher salt and fresh ground pepper; let sit for about fifteen minutes. Then marinate for about an hour in fresh lime juice, achiote paste, and cilantro.

• Grill the meat on a very hot skillet (or barbecue), for about eight minutes a side, but stay on top of it, as thinner cuts cook much faster – even four minutes a side;
• Let the meat sit for about ten minutes;

While the meat is sitting, prepare the tortillas in a separate skillet of butter and olive oil, hot, but not smoking, for a few seconds a side, turning frequently until the tortillas reach your desired state.

• cut the meat cross-grain, and serve with the tortillas for filling one-by-one, with tomatoes, cheese, lettuce, avocado, sour cream, and whatever your heart desires.

Easy and fantastic.