Roasted Sweet Potato with Garlic-Black Bean Sauce

canned black beans

½ cup(s), rinsed and drained

cilantro

1 tsp, fresh, chopped

garlic

1 clove(s), minced

red onion

2 Tbsp, minced

fat free sour cream

2 Tbsp

uncooked sweet potato

1 large, roasted and cut in half