Green-Bean and Prosciutto Negimaki

Preparation Cook haricots verts in a large pot of boiling salted water (3 tablespoons salt for 6 quarts water), uncovered, until just tender, 4 to 5 minutes. Drain, then transfer to an ice bath to stop cooking. Drain and pat dry. Force hard-boiled eggs through a medium-mesh sieve into a bowl using a rubber spatula. Stir in mayonnaise, zest, lemon juice, scallions, 1/2 teaspoon pepper, and 1/4 teaspoon salt (or to taste). Place a sushi mat with slats running crosswise or a 9-inch square of parchment paper on a work surface. Arrange 3 slices prosciutto perpendicular to slats and slightly overlapping to form a 9- by 7-inch rectangle. Spread about 1 tablespoon egg mixture evenly across bottom half of prosciutto rectangle. Arrange beans on egg side by side and end to end, overlapping ends, in 8 tight rows parallel to slats. Spread another tablespoon egg mixture over beans. Roll up prosciutto and beans tightly with aid of mat. Transfer roll, seam side down, to a cutting board, then trim ends and cut crosswise into about 10 (3/4-inch) pieces. Make and cut 4 more rolls. Turn pieces upright to serve. Cooks' note:Prosciutto rolls can be assembled (but not cut into pieces) 1 day ahead and chilled, each roll wrapped tightly in plastic wrap. Cut rolls while cold, then bring to room temperature, covered with plastic wrap, before serving, about 30 minutes.

Preparation Cook haricots verts in a large pot of boiling salted water (3 tablespoons salt for 6 quarts water), uncovered, until just tender, 4 to 5 minutes. Drain, then transfer to an ice bath to stop cooking. Drain and pat dry. Force hard-boiled eggs through a medium-mesh sieve into a bowl using a rubber spatula. Stir in mayonnaise, zest, lemon juice, scallions, 1/2 teaspoon pepper, and 1/4 teaspoon salt (or to taste). Place a sushi mat with slats running crosswise or a 9-inch square of parchment paper on a work surface. Arrange 3 slices prosciutto perpendicular to slats and slightly overlapping to form a 9- by 7-inch rectangle. Spread about 1 tablespoon egg mixture evenly across bottom half of prosciutto rectangle. Arrange beans on egg side by side and end to end, overlapping ends, in 8 tight rows parallel to slats. Spread another tablespoon egg mixture over beans. Roll up prosciutto and beans tightly with aid of mat. Transfer roll, seam side down, to a cutting board, then trim ends and cut crosswise into about 10 (3/4-inch) pieces. Make and cut 4 more rolls. Turn pieces upright to serve. Cooks' note:Prosciutto rolls can be assembled (but not cut into pieces) 1 day ahead and chilled, each roll wrapped tightly in plastic wrap. Cut rolls while cold, then bring to room temperature, covered with plastic wrap, before serving, about 30 minutes.