Puree 1 avocado, 3/4 cup buttermilk, 1 3/4 cups water, 1/2 teaspoon salt, and a dash of Tabasco until completely smooth and set aside. Add the juice of 1 grapefruit along with 1/2 cup each champagne vinegar and honey to a saucepan and simmer until thick. Chill the pan over ice, add the mixture to the blender, and process until combined. Serve it topped with fresh grapefruit chunks and herbs like basil or mint.
Recipe by Curtis Cooke, executive chef at Cal-a-Vie Health Spa in Vista, California