Slice the lemons as thin as you can get them. I use a food processor. Don't worry about seeds or the peeling you're going to strain everything.
Place lemon slices with peeling and seeds in a large bowl and add 2 cups sugar. Cover and allow to stand for 2 hours or up to 24 hours. Stir occasionally. I refrigerate after 2 hours if I'm not making it right then.
*Prepare pie crust now if you're making a homemade crust.
Allow the eggs and sugar mixture to come to room temperature before mixing the pie ingredients.
Preheat oven to 375 degrees.
Pre-bake pie crust for 15 minutes. Remove from oven and allow to cool while you mix the filling ingredients.
Strain the lemons. Using the back of a spatula, press as much liquid through the strainer as possible. You'll have about 2 cups of a sweet lemon-flavored simple syrup. (You can discard the peel, pulp, and seeds at this point.)
In the bowl of an electric mixer, beat eggs until light and foamy. They'll become a lighter yellow.
Add lemon sugar mixture to bowl with eggs and beat on medium speed for 2 minutes.
Pour into prepared pie crust.
Bake at 375 degrees for 35 to 40 minutes until the center is set, the top of pie is golden, and the crust is browned.
Allow to cool before slicing. Store pie in refrigerator for up to 1 week.