Beat the butter and sugar in a large bowl until light and creamy.
Stir in the eggs, vanilla, lemon rind and juice.
Fold in the flour and the salt.
Chill the batter for 1 hour.
(This will prevent it from spreading too much during baking.) Heat the oven to 350 degrees.
Lightly butter 2 baking sheets.
Drop the batter onto the baking sheets in teaspoon-fuls about 1 1/2 inches apart.
Bake for 6 to 7 minutes, until the edges are very lightly browned.
Take the cookies from the oven and let them cool on the baking sheets for 2 to 3 minutes.
Carefully transfer them with a metal spatula to wire racks to cool completely.