Mexican Soup

My good friend Kim gave me this recipe and it is delicious. I made is Christmas Eve and it was a hit (if I don't say so myself).
7-8 medium potatoes
1 large onion
1 large can stewed tomatoes drained
1-2 cans diced green chili's
1 bunch cilantro
1 pound Monterery Jack Cheese
1/2 cup butter
salt
pepper
garlic salt
oregano
1. Peel and cut potatoes, put in pan and cover with water
2. Add salt, pepper, garlic salt, 1/8 tsp oregano and 3 tbsp chopped cilantro leaves
3. Cook potatoes until tender, don't drain water
4. In frying pan melt 1/2 cup butter, add diced onions, drained tomatoes and green chili's - Saute until soft
5. Add to soup onion, tomatoes, green chili mixture
6. simmer 20 minutes
7. Turn off heat and add 1/2 lb cheese cut in chunks until melted
8. Add the other 1/2 lb cheese chunks just before eating