In a large mixing bowl, start by combining the sour cream and mayonnaise. These are the base of your dip, and they’re going to give it that creamy, smooth texture. Stir them together until they’re well blended. Then, add the lime juice, chili powder, garlic powder, and cayenne pepper (if you’re using it). This is where the flavor really starts to come together! The spices add just the right balance of warmth and tanginess.