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.