Add diced onion and bell pepper; cook until softened. Add garlic and cook briefly.

Stir in tomato sauce, ketchup, tomato paste, Worcestershire, mustard, vinegar, spices, and optional brown sugar.

Reduce heat and simmer until thick, stirring occasionally.

Taste and adjust seasoning (salt/pepper, more vinegar for tang, more ketchup for sweetness).

Spoon filling onto toasted buns and serve.