Marinate the steak with the oil saving 1 tablespoon, Worcestershire sauce, salt and pepper and set aside for one hour.
Preheat a large cast iron pan until very hot.
Sauté the onion and peppers with a tablespoon of oil. Salt and pepper to taste. Set aside.
Roast the pearl potatoes until roasted. Set aside.
Grill the meat on the very hot pan to the desired doneness. Top with the guacamole and the shredded cheese and cover until cheese melts.
Serve with the potatoes and peppers, flour tortillas, lime wedges and some extra salsa.