Dissolve 1/4 cup cornstarch in 1/4 cup cold water.
Boil 1 1/2 cups water and add cornstarch mixture along with:
1 1/2 cups sugar
1 T. butter
2 T. lemon zest
Cook over medium heat until mixture clears.
When cool, beat in:
1/4 cup lemon juice
Proceed as for any 2 crusted pie.