Combine 1 1/2 cups sugar, cornstarch, and salt in a heavy saucepan. Gradually add milk, stirring until blended. Cook over medium heat, stirring constantly, until thickened and mixture comes to a boil.

Boil gently 1 minute, stirring constantly. Remove from heat.

Preheat oven to 350 degrees. Beat egg yolks at hight speed of an electric mixer until thick and lemon-colored. Gradually stir about 1/4 of hot milk mixture into yolks; add this to remaining hot mixture, stirring constantly. Cook over medium heat, stirring constantly, for 2 to 3 minutes. Remove from heat; stir in lemon rind, lemon juice, and butter, stirring until butter melts. Pour filling into baked pie shell.

Beat the 4 egg whites and cream of tartar at high speed of an electric mixer until foamy. Gradually add remaining 1/4 cup plus 2 Tbsp.

sugar, 1 Tbsp. At a time, beating until stiff peaks form. Spread meringue over hot filling, sealing to edge. Bake for 12 to 15 minutes, or until browned. Cool before cutting.

Carlson -