Thaw pie crust (if using frozen) 10 minutes. Prick bottom and sides thoroughly with fork. Bake in 400 degree oven for 10 minutes or until nicely brown.
In medium saucepan, combine the 1 1/2 C sugar, cornstarch, flood and salt. Gradually stir in water. Cook & Stir over medium heat until thickened and bubbly (it thickens fast and may tend to stick to pan so don't leave it). Reduce heat & Cook 2 minutes more. Remove from heat. Beat eggs yolks slightly. Stir about 1 cup of the hot mixture into the beaten yolks. Return mixture to saucepan & Cook & stir 2 minutes more. Remove from heat.
Stir in butter or margarine & lemon peel. Gradually stir in lemon juice mixing well. Pour into baked pie crust. Spread Meringue on top of hot filling, sealing to edges of pastry. Bake in 350 oven for 12 to 15 minutes. Cool & Chill.
MERINGUE: In mixer bowl beat egg whites, vanilla & cream of tartar till soft peaks form (tips curl over). Gradually add 6 Tablespoons sugar, beating to stiff peaks.