How to Make It
Heat the oil in a medium saucepan over medium heat. Add the onion and garlic and cook, stirring frequently, until softened, 3 to 5 minutes.
Add the ketchup, vinegar, molasses, brown sugar, mustard, Worcestershire sauce, chili powder, cayenne (if using), ¾ cup water, ¼ teaspoon salt, and ½ teaspoon black pepper and simmer gently, stirring occasionally, until slightly thickened, 12 to 15 minutes. The sauce will keep in the refrigerator for up to 2 weeks.