Preparation Force eggs through a sieve into a small bowl and gently toss with onion. Trim 36 pumpernickel slices to 1 1/4-inch squares, then top each with 1/2 teaspoon sour cream, 1/2 teaspoon egg, and 1/2 teaspoon caviar. Cooks' notes:• Eggs can be boiled 2 days ahead and chilled. Mince onion and add to egg within 1 hour of serving. • Pumpernickel squares can be cut 1 day ahead and kept, wrapped tightly in plastic wrap, at room temperature.
Preparation Force eggs through a sieve into a small bowl and gently toss with onion. Trim 36 pumpernickel slices to 1 1/4-inch squares, then top each with 1/2 teaspoon sour cream, 1/2 teaspoon egg, and 1/2 teaspoon caviar. Cooks' notes:• Eggs can be boiled 2 days ahead and chilled. Mince onion and add to egg within 1 hour of serving. • Pumpernickel squares can be cut 1 day ahead and kept, wrapped tightly in plastic wrap, at room temperature.