2 tablespoons unsalted butter |
1/2 cup finely diced onion |
4 garlic cloves, finely diced |
6 plum tomatoes, coarsely chopped |
1/4 cup ketchup |
1/4 cup water |
2 tablespoons english mustard |
2 tablespoons dark brown sugar |
3 tablespoons treacle (may substitute molasses) |
2 tablespoons tamarind paste |
1 teaspoon cayenne pepper |
1 tablespoon dried ancho chile powder |
1 tablespoon paprika |
1 tablespoon worcestershire sauce |