Sonora, one of Northern Mexico states, is home of this very particular way of making refried beans. Flavor is more "complex" and rich than regular refried beans, can be served at breakfast/lunch as side for scrambled eggs or by itself with flour tortillas or totopos and your favorite fresh salsa on the side.
1Place clean pinto beans in a large bowl, add water to cover and let beans soak overnight.
2Drain beans and throw soaking water. In a large pot add 3 quarts, half onion and garlic cloves. Bring to a boil over medium high heat; reduce to low and simmer 90 minutes or until tender.
3Meanwhile, place ancho chilies in a large bowl with warm water to cover, soak 30 minutes, stem, seed and puree the chilies, set aside.
4Heat lard or oil in a large heavy skillet over medium high heat. Fry chorizo to a light brown. Add the rest 1 1/2 onion chopped, cook 3 more minutes until onion is transparent. Add the ancho puree and finely chopped olives. Cook, stirring frequently, about 5 minutes until a thick sauce forms.
5Drain pinto beans and puree in a blender along with onions and garlic and a little of the cooking water.
6Reduce heat to medium and stir in the bean puree. Cook about 5 more minutes, reduce heat to low and stir in shreded Monterey Jack. Cook about 10 minutes, stirring frequently, until the bean mixture is thickened and the cheese is melted. Serve hot with flour tortillas.