Prepare Sauce
Toast the guajillo chiles in a dry skillet (cast iron is best) over high heat just until soft and fragrant, about 10 seconds on each side.
Heat the oil in a saucepan over high heat and saute the onion until lightly browned, about 10 minutes. Add the guajillo chiles and the remaining sauce ingredients and bring to a boil. Reduce the heat and simmer for 20 minutes.
Puree the sauce in an electric blender or food processor and strain through a fine sieve. Set aside.
Assemble Enchiladas
Preheat Oven to 350F
Saute chorizo and onion in a skillet over high heat, breaking up the meat, until the meat is thoroughly cooked, about 10 minutes.
Stir in the potatoes and remove from the heat.
Heat about 1 to 2 cups of oil in skillet. Use a pair of tongs and dip a tortilla in the oil for a few seconds until softened. Transfer to a plate atop a few layers of paper toweling to drain.
Place 3 to 4 tablespoons of the filling on each tortilla and roll them up tightly.
Spread about 1 cup of the guajillo sauce in the bottom of a large baking dish and place the enchiladas seam-side down in the dish. Cover with about 2 cups of the sauce and sprinkle with the shredded cheese.
Bake in oven for 15 to 20 minutes until cheese is melted and enchiladas are heated through.