2 tbsp. butter
3 stalks celery, diced
1 onion, cut fine
2 tbsp. vinegar
2 tbsp. brown sugar
4 tbsp. lemon juice
1 1/2 c. catsup
1/2 c. water
3 tbsp. Worcestershire sauce
1/2 tsp. mustard

Melt butter. Add celery and onion. Cook until onion browns and celery is tender. Add vinegar, brown sugar, lemon juice, catsup, water, Worcestershire sauce and mustard. Simmer these ingredients. Add salt and pepper, then sliced roast beef.