1Place the steak, jalapenos, taco sauce, onion and lime juice in a resealable bag or marinating container. Marinate overnight or up to 48 hours
2Prepare your grill according to manufacturer's instructions. Spray a grill basket with nonstick grill spray. Add the contents of the marinating container. Using tongs, continuously toss the meat until it is fully cooked and starting to crisp around the edges.
3Divide the meat, onions and peppers among the tortillas. Top with watercress, radish, avocados and cheese. Serve immediately.