If you don't have buttermilk, you can make your own by thinning an equal amount of yogurt with milk. Be sure to use full-fat sour cream here, as it's important for the dip's consistency. Plus, fat-free sour cream tends to taste watery. Serve this with homemade soft pretzels, chicken wings, pizza, grilled chicken, tomato salad, or anything else you think needs a zippy, herbaceous dip. It's not a bad idea to double this recipe because, well, extra dip is never a problem.