Ingredients

2 tablespoons vegetable oil 

1 small white onion, diced small 

3 garlic cloves, finely chopped 

1 can (6 ounces) tomato paste 

2 teaspoons ground mustard 

1 can (28 ounces) tomato sauce 

1/4 cup unsulfured molasses 

2 tablespoons Worcestershire sauce 

3 tablespoons white vinegar 

2 teaspoons coarse salt 

1 1/2 teaspoons ground pepper 

Preparation

In a medium saucepan, heat oil over medium. Add onion and cook until completely soft, about 5 minutes. Add garlic and cook until fragrant, 1 minute.

Add tomato paste and mustard; cook, stirring constantly, until paste turns a brick-red color, about 5 minutes. Add 2 cups water, tomato sauce, molasses, Worcestershire, vinegar, salt, and pepper and stir until smooth.

Bring to a simmer; reduce heat to low and partially cover. Simmer, stirring occasionally, for 2 hours (thin with water if sauce becomes too thick). Season to taste with vinegar, salt, and pepper. Let cool completely before using.