1 (8 1/2 oz.) can pineapple tidbits
2 tbsp. brown sugar
1/2 tsp. ground ginger
1/2 c. chopped onion
1/3 c. cider vinegar
3 tbsp. soy sauce
2 tbsp. oil
1 tbsp. Lea & Perrins Worcestershire sauce
5 lb. beef chuck arm pot roast
1 (10 1/2 oz.) can condensed beef broth
1 1/2 tsp. salt
3 c. peeled sweet potato chunks
2 tbsp. cornstarch
2 tbsp. cold water

Combine pineapple, brown sugar, ginger, onion, vinegar, soy sauce, oil, and Lea & Perrins. Place beef in a snug-fitting bowl or doubled plastic bag. Pour pineapple mixture over meat. Cover or fasten. Refrigerate for 12 hours, mixing or turning once. Place beef and the pineapple marinade in a large saucepot or Dutch oven. Add broth and salt. Bring to boiling point. Reduce heat and simmer, covered, for 1 1/2 hours. Add sweet potatoes. Simmer, covered, for 1/2 hour. Remove beef to a warm platter. Blend cornstarch with water. Stir into liquid in saucepot. Cook and stir until sauce thickens. Serve hot with the pot roast.