Add your guajillo peppers, ancho chile peppers, arbol peppers, onion, and garlic to a saucepan with plenty of water to cover and cook over medium heat for about 20 minutes or until the peppers soften up.
Remove peppers from pot. Under running water, remove all seeds from peppers. Remove stems. Add all peppers, onion, garlic and reserved broth to a blender and blend until smooth. Strain sauce through a strainer to remove extra seeds and skin. You will now have a sauce.Add sauce to shredded beef and mix together. Season with salt to taste.