Zest just enough of the lemon rind to get the 1 teaspoonful you need.
Remove the rest of the rind and the white pith from the lemon, and slice it very thin (the slicer attachment of a Cuisinart works great). You should have about 1/3 cup of slices.
In another bowl, combine the sugar, flour and salt. Blend in the softened butter and mix thoroughly.
Crack the eggs, reserving 1 teaspoon of the white to use on top of the pie before it goes in the oven. Set that aside. Beat the eggs well. Add them to the flour-sugar mixture.
Add the water, zest, and lemon slices, along with their juices, to the flour-sugar mixture. Blend well.
Preheat the oven to 400.
Roll out the bottom crust and line a 9-inch pie pan with it. Pour the filling into the unbaked pie shell. Top with the top crust, rolling and crimping the edges. Chill well, about 10-15 minutes in the freezer or 20-30 minutes in the refrigerator. Take the pie out and brush it with the egg white and sprinkle it with sugar.
Bake at 400 for 30-35 minutes.