Beat egg yolks. Beat in lemon peel, lemon juice and milk. Add sugar, flour and salt. Beat until smooth.
Beat egg whites until stiff peaks form. Add 1/3 of the egg whites to to the lemon mixture and bet them together thoroughly.
Fold the lightened lemon mixture into the remaining egg whites until no streaks remain.
Pour into pastry and bake at 350 until golden brown. 45 to 50 minutes. (A layer of lemon will settle to the bottom and a soft meringue-like topping will float to the top. Center will be jiggly, but will set upon cooling.