Refried Beans

Ingredients:

1 1/4 cups white beans (canned) or optional *dried pinto beans, soaked overnight in water
1/4 cup water
2 onions
4 cloves garlic
2 tbs butter
1 tsp ground cumin
1 tsp ground coriander
1 tsp chili powder
small bunch of fresh coriander
fresh coriander and sour cream to serve