Cream butter and sugar then add lemon rind and lemon juice. Add egg and beat well. Combine the flour, salt and soda and gradually blend into the butter and sugar mixture. Make 2 "logs" of dough about 1 1/2" in diameter.

Wrap logs in waxed paper and refrigerate until firm. Preheat oven to 400 degrees. Cut logs into thin slices and place on greased cookie sheet. Lower heat to 350 degrees and bake for about 5 minutes.