My Greek Tzatziki Sauce

1 C plain nonfat or greek yogurt
1 C sour cream
3 tsp minced garlic
2 tbsp minced fresh dilll or 2 tsp dry dill
1/4 tsp salt
dash pepper
2 tbsp horseradish sauce, optional
1 tsp red chili flakes or powder, optional

Combine all ingredients in a small mixing bowl. Cover and chill well before serving. Best if made the day before so the flavors can marry better..