Hard-boil 6 eggs, then peel and slice in half. Scoop the yolks into a food processor and puree with 1 cup watercress leaves, 1/4 cup mayonnaise, 2 tablespoons each chopped scallions and tarragon, and salt and pepper. Cut 4 slices ham into thin strips; fold and place in the hollowed-out egg whites. Fill with the yolk mixture.
Photograph by Stephanie Foley