1 lb. lean ground beef
1 onion, diced
1 cup celery, chopped
1/2 cup ketchup
1 cup grated cheddar cheese
salt and pepper, to taste

Cook everything except cheese together until done. Add cheese and stir until melted. Spread buns with mayonnaise or mustard and add mixture. Wrap each bun in foil and heat in 350°F oven for about 20 minutes.