Stir together the mayonnaise, sour cream, buttermilk, lime juice, garlic, Serrano pepper, cilantro, chives, and cayenne. Taste and add salt and pepper.
I like my dressing on the thinner side, so if you prefer it thicker use 1/2 cup of mayonnaise. And if you don’t want it to be so spicy, feel free to omit the Serrano or substitute a jalapeno pepper instead. Also, you can use parsley instead of cilantro if you’re one of those “Cilantro tastes like soap people, I won’t be insulted.