Sauté onion in drippings in a heavy skillet over low heat until tender. Add meat; cook over low heat until meat is browned, stirring to crumble. Drain off pan drippings; discard.
Add tomatoes, green pepper, Worcestershire sauce, sugar, salt, and pepper, mixing well. Cook, uncovered, over low heat 45 minutes, stirring occasionally. Serve over hot cooked rice.