Season: Rub the meat with salt and pepper, then place it in a large baking dish or Dutch oven to cook in the oven (Make sure it is big enough to add the meat and about 6 cups of water if making it soupy.
Prepare the peppers: First, clean and devein all the peppers with the help of scissors.
Roast and toast: Then, heat a skillet over medium-high heat. Slightly roast the peppers, ensuring you do not burn them; this step will take 1 - 2 minutes.
Note: Burned peppers make the dish taste bitter.
After you finish the peppers, soak them in a medium bowl with hot water for 20 minutes.
Next, roast the tomato, onion, and garlic and place them in your blender. Then, toast the whole cloves, cumin seeds, and black peppercorns (a quick step that only takes a few seconds).
Make the sauce: Finally, place the roasted tomatoes, dried herbs, onion, cinnamon, vinegar, and the rest of the spices in a blender.
Once the peppers are soft, drain, add to the blender, and process until you have a smooth sauce.
Note: Add a few tablespoons of water if your blender has difficulty processing it.
Put all together: Pour the sauce over evenly over the meat, and cover the baking dish with aluminum foil. And stir well. Make sure to cover all the pieces of meat 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 the meat to absorb the flavors of the sauce.
Bake your Birria: Preheat the oven to 350º F. Bake for about 4 hours until the meat is fork-tender and reaches an internal temperature of 160ºF.
Note: If your baking dish is too small to add the water, you can always use a bigger dish or a Dutch oven.
Before Serving: Remove the baking dish or pot from the heat when the meat becomes tender. Taste your birria and adjust the salt and pepper to your taste. Then, with the help of two forks, slightly shred the meat.