Combine the eggs and sugar in the top of a double boiler; beat until frothy, using an electric mixer set at medium speed.
Place over simmering water and beat until the mixture is warm.
Remove from the heat and continue beating until the eggs are foaming and the bubbles are fine-textured.
Add the lemon rind.
Sift together the flour and salt; gradually fold in.
Drop by half teaspoonfuls on a greased and floured cookie sheet, leaving an inch between them.
Swirl with the back of the spoon into circles.
Dust the cookies with confectioners' sugar put through a sieve.
Sprinkle a few pine nuts (3 or 4) on top.
Let stand 10 minutes.
Bake in a 325° oven for 10 minutes, or until a creamy golden color on the bottom.(Over-baking will make these cookies hard.)