Brown and crumble ground beef in a large non-stick skillet over medium-high heat. Drain any grease. Add Worcestershire sauce, ketchup, minced onion and salt and pepper to beef. Stir to combine.
Reduce heat to low and let mixture heat thoroughly, about 5 minutes or so.
Sprinkle some cheddar cheese down the center of each tortilla. Add a few heaping Tablespoons of the beef mixture on top of cheese. Drizzle a little mustard (and more ketchup, if desired) on top of the beef, and then add a couple tomato slices. Roll up each tortilla burrito-style.
Place wraps, a couple at a time, onto a preheated indoor grill and grill for 3-5 minutes, or until cheese is melted. Carefully remove wraps from grill and place on a plate. Gently unravel wrap to add some lettuce. Re-roll wrap and then cut in center diagonally. Serve immediately and enjoy! ♥