Place the guajillo peppers in a medium saucepan with the 2 cups of water over a medium-high heat. When water starts boiling turn heat down and simmers for 5 minutes. Remove saucepan from heat, cover and set aside.
Remove pork tenderloin from package and pat dry with pepper towels. Heat oil in a 12-inch nonstick skillet over medium-high heat until hot. Cook tenderloin until well browned on all sides, about 10-15 minutes. Transfer pork to a large plate and cover with aluminum foil forming a tent. Let it rest.
Meanwhile, chop tomatoes and onion, place in a blender along with chipotle peppers, peanuts, garlic cloves, cinnamon, black peppercorns, drained guajillo peppers and chicken broth. Process until smooth.
Drain rendered fat from the skillet and reserve. Using a pepper towel wipe any residue of the meat on the skillet. Return the reserved fat and turn heat to medium and pour peanut sauce using a strainer.
Once the sauce starts boiling add the pork tenderloin, reduce heat and simmer, about 20-25 minutes. Turning meat halfway the cooking time. Stir occasionally to avoid the sauce from sticking to the bottom.
Remove skillet from heat and let pork rest in the sauce for 5 minutes, then slice ½ inch thick. Serve, with rice or black beans and drizzled pork meat with the peanut sauce.