Makes 24 stuffed eggs.
Cut a paper-thin slice off the ends of each egg and halve the eggs crosswise. Force the yolks through a sieve into a bowl and stir in the mayonnaise, the sour cream, the lemon juice, and salt and pepper to taste. Transfer the filling to a pastry bag fitted with a large decorative tip and pipe it into the egg whites, mounding it. The stuffed eggs may be made 1 day in advance and kept covered and chilled. Just before serving, top the eggs with the caviar.