Crudités with Green Goddess Dip

Name: Crudités with Green Goddess Dip
Ingredients: 3 anchovy fillets (preferably salt-packed); Sea salt and freshly ground pepper; 1 cup (8 oz./225 g) mayonnaise (preferably homemade); 1/2 cup (4 oz./125 g) nonfat yogurt; 1 ripe avocado; 1 garlic clove, minced; 3 Tbs. minced fresh chives; 1/4 cup (1/2 oz./15 g) minced fresh flat-leaf parsley; 1 Tbs. minced fresh tarragon, plus tarragon leaves for garnish; 1/4 cup (1 oz./30 g) chopped green onions, white and green portions, plus more for garnish; Crudités for serving