Toast the chilies: Lightly toast the dried guajillo, ancho, and mulato chilies in a skillet until fragrant.
Rehydrate chilies: Soak the toasted chilies in warm water for 20 minutes.
Char the aromatics: Roast the onion, garlic, and tomatoes until lightly charred.
Blend the sauce: Combine the chilies, roasted aromatics, vinegar, oregano, cumin, cinnamon, and beef broth in a blender. Blend until smooth.
Simmer the sauce: Pour the blended sauce into a pot and simmer for 15–20 minutes to thicken and blend the flavors.
Use or store: Use immediately or store in the refrigerator for up to 5 days.