In a medium saucepan, mix lemon juice, onion, distilled white vinegar, water, brown sugar, prepared mustard, ground black pepper, salt, cayenne pepper and vegetable oil. Bring to a boil, then simmer uncovered 20 minutes.
Stir ketchup, Worcestershire sauce and liquid smoke flavoring into the mixture. Return to boil, then remove from heat. Refrigerate until ready for use.
Irene's Barbeque Sauce · Dinner Match Lab | Dinner Match Lab