Place peeled and cut potatoes into a large pot. Cover completely with about 2
inches of water. Add chiles and onion. Salt and pepper to taste. Cover and boil
over medium heat until potatoes are completely done.
Mash potatoes slightly; add
butter. Simmer, covered, for about 1 hour.
Serve hot soup over grated Monterey jack cheese.
This goes well with Mexican
cornbread, warm flour tortillas or chips and salsa.