1 Preheat the oven to 400 F.
2 Add the asparagus to a large skillet of lightly salted boiling water and simmer for about 3 minutes, then drain and refresh under cold running water. Trim to 4-inch lengths.
3 Combine the salt, black pepper and lemon rind in a shallow dish and roll each sparagus spear lightly in this mixture.
4 Cut the puff pastry sheets into 5x2-1/2 inch rectangles and place one asparagus spear. In a bowl, combine the egg yolk with 2 teaspoons water and brush on the sides and ends of the pastry. Roll the pastry up like a package, folding in the sides so that the asparagus is completely sealed in. Press the seams of the pastry using a fork.
5 Place the pastries on lightly greased baking sheets. Brush with the remaining egg and sprinkle lightly with the sesame seeds.
6 Bake the asparagus pastries for about 15-20 minutes, or until golden brown. These pastries are delicious served warm or cold.