Make this for our Breakfast Enchiladas.
Toast New Mexican and guajillo chiles in a dry large cast-iron skillet over medium-high heat, turning, until warm and soft, about 30 seconds per side (do not let blacken, or chiles will be bitter). Remove chiles; reserve skillet.
Discard stems; cut chiles lengthwise with kitchen shears, and discard seeds. Cover chiles with boiling water. Let stand until hydrated, about 20 minutes.
Meanwhile, cook garlic and tomatoes in skillet over medium-high heat, turning, until charred and soft, about 10 minutes. Set tomatoes aside; peel garlic.
Heat oil in skillet over medium-low heat until hot but not smoking. Cook onion until translucent, about 5 minutes. Add chile powder; cook 1 minute. Drain chiles, reserving 1 1/2 cups liquid.
Puree onion, hydrated chiles, chipotle chiles, tomatoes, garlic, and oregano in a blender, adding a small amount of the reserved soaking liquid if mixture seems dry. Pass sauce through a fine sieve into skillet.
Cook over medium heat, stirring, 5 minutes. Add remaining soaking liquid. Simmer until sauce is thickened, 12 to 15 minutes. Season with salt. If not serving immediately, refrigerate up to 2 days. Just before serving, heat over low heat; add water if sauce seems too thick.
Be sure your kitchen is ventilated when you soak the New Mexican and guajillo chiles (the latter is especially fiery); the vapors can be a mild irritant. When working with chiles,remember to wear protective gloves.