Curry Sauce

2 pounds onions, chopped

4 cloves garlic, minced

3 tablespoons minced ginger

1 (14.5 ounce) can diced tomatoes

1 tablespoon turmeric powder

2 tablespoons cumin

1 tablespoon garam masala

1 tablespoon curry paste

1 teaspoon red pepper flakes

Place onions and garlic into a large saucepan, add water to cover. Place over high heat and bring to a boil, reduce heat to medium-low, cover, and simmer for 45 minutes. Add the ginger, and continue simmering for 5 more minutes.

Puree the onion in a food processor or blender in batches until smooth. Place a large saucepan over medium-high heat, pour in the diced tomatoes, and season with turmeric, cumin, garam masala, curry paste, and red pepper flakes. Bring to a simmer, then pour in the onion puree. Simmer for 45 minutes.