Sour Lemon Pie

This was my grandpa's favorite dessert. My grandparents had a lemon tree in their backyard in California. My grandma would pick lemons from the tree to make lemon pie. After she passed away every time I would visit my grandpa I would try to make him a lemon pie.

1 1/2 cups sugar
5 Tbs. flour
5 Tbs. cornstarch
1 1/4 cups water
3 eggs
2 Tbs. butter
1 to 2 tsp. finely shredded lemon peel
2/3 cup lemon juice
Baked pastry shell

For filling: in a medium saucepan combine sugar, flour,cornstarch and dash of salt. Gradually add water. Cook and stir over medium-high heat till thick and bubbly. Reduce heat and stir for 2 minutes more. Remove from heat. Separate egg yolks, discard whites (I don't like meringue). Beat egg yolks. Gradually stir in one cup of the filing into the yolks. Pour the egg mixture back into the filling. Bring to boil. cook and stir 2 minutes more. Remove from heat. Stir in butter and lemon peel. Gradually stir in lemon juice. Pour filling into baked pastry shell. Refrigerate. Serve with whipped cream