Stewed Tomatoes Spiced with Mustard

12 roma (plum) tomatoes - peeled, quartered, and seeded

¼ onion, minced

⅓ cup water

½ teaspoon mustard seed

⅓ teaspoon dry mustard powder

1 large clove garlic, minced

1 bay leaf

⅛ teaspoon ground black pepper

½ teaspoon soy sauce

salt to taste

Combine tomatoes, onion, water, mustard seed, mustard powder, garlic, bay leaf, and black pepper in a large, heavy pot over medium heat; bring to a simmer and cook for 10 minutes. Stir soy sauce through the tomato mixture; continue cooking another 5 minutes. Season with salt. Remove bay leaf to serve.