2 tablespoons peanut oil
1 tablespoon margarine
1 large onion, chopped
1 tablespoon minced fresh ginger root
2 tablespoons minced garlic
1 teaspoon ground cinnamon
1 teaspoon ground black pepper
2 tablespoons ground coriander
2 tablespoons ground cumin
1/4 teaspoon ground turmeric
1 teaspoon cayenne pepper
2 tomatoes
2 serrano chile peppers, seeded
1/2 cup fresh cilantro
1/2 cup yogurt, whisked until smooth
3 cups water