How to Make It
Toast chiles in a hot oven (400°) for 3 or 4 minutes. Shake out seeds. Cover with 5 cups warm water; soak until soft. Place chiles and water in a blender with garlic, oil, salt, oregano, and cumin. Whirl until smooth (or grind in a food processor). Pour into a pan; add tomato purée. Simmer 10 minutes.