Adapted from millerfamilyorganizer.blogspot.de
Brown ground beef in large skillet and drain. Add Worcestershire sauce, ketchup, dried onion, and salt and pepper to the beef and simmer for 5 minutes. Sprinkle shredded cheese down center of each tortilla. Add a few heaping tablespoons of the beef mixture on top of the cheese. Spread some mustard on top of the beef along with some slices of tomato. Roll up tortilla burrito-style and place wraps on preheated indoor grill (I used my George Foreman). Grill wraps for about 5 minutes until cheese is melted. Cut on a diagonal and serve immediately.