Preheat oven to 400 degrees F (205 degrees C). Peel and dice potatoes. In a bowl, toss diced potatoes together with cumin, chili powder, salt, and ketchup, and place in an oiled baking dish. Bake in the preheated oven for 20 to 25 minutes, or until tender.
Meanwhile, boil tomatillos and chopped onion in water to cover for 10 minutes. Set aside to cool. Once cooled, puree with half of the cilantro until smooth.
Fry tortillas individually in a small amount of hot oil until soft.
Mix potatoes together with pinto beans, 1/2 cheese, and 1/2 cilantro. Fill tortillas with potato mixture, and roll up. Place seam side down in an oiled 9x13 inch baking dish. Spoon tomatillo sauce over enchiladas, and spread remaining cheese over sauce. Bake for 20 minutes, or until hot and bubbly.