Green Goddess Dressing and Dip

Combine sour cream, mayonnaise, anchovy, parsley, basil, white and pale-green parts of scallions, 1/2 teaspoon salt, and a pinch of pepper in a food processor and puree until smooth. Transfer to a bowl.

Finely chop scallion tops and stir into dressing along with tarragon. Season with salt and pepper and serve with crudites or crostini.