BON APPETIT

INGREDIENTS
½ bunch watercress, tough stems removed, coarsely chopped (about 2 cups)
4 anchovy fillets packed in oil, drained
½ cup mayonnaise
2 tablespoons sour cream
½ cup (lightly packed) fresh flat-leaf parsley leaves
2 tablespoons chopped fresh chives
2 tablespoons chopped fresh tarragon
1 tablespoon white wine vinegar
Kosher salt and freshly ground black pepper