Preheat oven to 400 degrees F (205 degrees C). In a bowl, toss diced potatoes together with ketchup, cumin, chili powder, garlic salt, and cayenne, and place in a lightly oiled baking dish. Bake for 20 to 25 minutes, or until tender.
Meanwhile, mash pinto beans in a mixing bowl with a potato-masher. When potatoes are done, add to the mashed pinto beans and mash all together. Add most of the chopped cilantro, leaving just enough to sprinkle on top after you pull the enchiladas out of the oven.
Grab yourself a tortilla and stuff it, I mean, no whimpy enchiladas. Fill that sucker. Roll it up and place in baking dish seam side down. Continue rolling until you have used up all the mixture. Pour tomatillo salsa over the entire pan of enchiladas until you’ve got a good coat on em.
Bake for 20 minutes, pull out, sprinkle with the shredded sharp cheddar cheese and stick it back in until it’s melted.
Pull out the enchiladas and sprinkle with remaining cilantro.
Serve with sour cream.