Barbecues Beef or Pork

1/4 c. butter
1 c. chopped onion
3 1/2 c. tomato puree
1/2 c. packed brown sugar
1/4 c. Worcestershire sauce
2 Tbsp. lemon juice
1 Tbsp. prepared mustard
1/2 tsp. salt
4 to 5 pounds beef or pork cooked and sliced thin

Saute onion in butter in saucepan until tender; add tomato puree, brown sugar, Worcestershire sauce, lemon juice, mustard, and salt.  Simmer over moderate heat for 30-40 minutes.  Add meat slices.  Heat 1015 minutes.  Spoon barbecued meat slices over buttered, toasted, bun halves.  Makes 10 to 12 sandwiches.