For the crust:
1 cup butter, softened
1/2 cup white sugar
2 cups all-purpose flour
pinch of table salt
For the filling:
1 1/2 cups white sugar
1/2 cups all-purpose flour
2/3 cups lemon juice (about 3 large, or 5 small
zest from two lemons (large, or 3 if small)
for garnish - powdered sugar for dusting, and very thin twists of sliced lemon, or a tiny sprig of mint
Preheat oven to 350F.
In a mixing bowl, mix together softened butter, 2 cups flour and 1/2 cup sugar. Press this mixture into the bottom of an ungreased 8x11 inch baking pan. This will form the crust for your bars.
Bake for 20 to 25 minutes in the preheated oven. You're looking for the crust to become firm, and evenly light, toasty, golden brown.
In a separate bowl, whisk together the remaining 1/12 cups sugar and 1/2 cup flour. Whisk in the eggs, lemon juice and lemon zest. If you wish, you can add a drop of yellow food coloring to create a pale, lemony yellow filling, but it isn't necessary. Pour over the baked crust.
Bake for an additional 20 to 25 minutes in the 350F oven. The bars will firm up as they cool, and once they've cooled to room temperature, you can stash them in the fridge. The consistency of the filling will be about that of a firm pudding.