Lamb Braised in Yogurt and Cream-Rogani Gosht

1 cup plain yogurt (or sour cream)
1 cup heavy cream
2 medium onions, coarsely chopped
1/4 cup blanched almonds
2 tablespoons chopped fresh ginger
2 tablespoons ground coriander
1 tablespoon ground cardamom
Salt and freshly ground pepper to taste
2 lb. boneless lean lamb, cut into 1-2 inch pieces
2 large potatoes, peeled and quartered

Combine all ingredients except the lamb and potatoes in a blender or food processor and process until smooth.

Put the yogurt mixture and the lamb into a large, heavy pot (preferably nonstick) and bring to a boil over moderate heat. Reduce the heat and simmer tightly covered for 2 hours.

Check the mixture and stir frequently, adding milk or water as needed if the sauce becomes too thick. Add the potatoes and continue cooking until tender, 30 to 45 minutes.

Serve with your favorite rice.