In 1 qt micro-safe casserole, combine beans, cheese, salsa, chili powder and cumin. Microwave 2 minutes. Stir. Microwave 1 to 3 minutes longer or til mixture is heated through and cheese melts.

Transfer to serving dish and spoon sour cream onto center of bean mixture. Garnish with chopped green onion and fresh cilantro sprigs, if desired. Serve hot, with tortilla chips for dipping.