Birria is usually made with goat’s meat or even with lamb or a combination of several types of meat. The use of a combination of meats is common in restaurants or local Birria eateries known as “Birrierias”.
Season the meat with salt and pepper, then place in a large baking dish.
Clean and devein the peppers. Slightly toast them over a medium heat, making sure you do not burn them (burned peppers make the dish taste bitter). Soak peppers in a cup of hot water for 20 minutes. Roast the onion and garlic and place in your blender.
Toast the whole cloves, cumin seeds, and black peppercorns (this is a quick step that only takes a few seconds). Place them in your blender along with the roasted tomatoes, herbs, onion, cinnamon and the vinegar.
Once peppers are soft, drain, add to the blender and puree until you have a smooth sauce. Add a few tablespoons of water only if your blender is having a hard time processing it. Season the sauce with salt.
Pour the sauce over the meat, making sure it is covered all over with this sauce of dried peppers and spices. Cover the baking dish with aluminum foil and refrigerate overnight or for at least 4 hours to allow all the meat to absorb the flavors. SEE NOTES about adding more water.
PPreheat the oven to 350º F. Bake the meat in the baking dish covered with the aluminum foil for about 4 hours or until it is fork-tender.
Serve the warm meat with its broth in bowls and garnish with chopped onion and cilantro. Serve with warm tortillas and a a hot salsa. Any leftover Birria will be great the next day to make Birria Quesadillas.