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 (or squirt) some yellow 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 use my Cuisinart).
Grill wraps for about 5 minutes until cheese is melted. Cut on a diagonal and serve immediately!