Julie’s BBQ Beef on a Bun

Combine in a large pan:
1 large ketchup
¼ C. butter
1/3 C. vinegar
¼ C. brown sugar
1/3 C. white sugar
¼ C. grated onion
¼ t. garlic powder
¾ t. black pepper
1 roast, cooked and sliced thin
Simmer 30 minutes.
Serve on hot buns.