Heat the oven to 400°F and grease a 9-by-13-inch dish.
Brown the beef, onion and pepper in a large skillet, breaking the meat into fine crumbles. Drain excess fat and add the garlic for 30 seconds.
Stir in tomato sauce, ketchup, vinegar, brown sugar, mustard, Worcestershire and salt. Simmer for 8 to 10 minutes until thick.
Spread the filling in the dish and arrange the frozen tater tots in a single close layer.
Bake for 35 to 40 minutes, until the potatoes are dark golden and the filling bubbles. Rest 10 minutes before serving.