8tablespoons(1/2 pound or 1 stick) unsalted butterat room temperature (or dairy-free margarine - Smart Balance)
5large eggsat room temperature
Using a vegetable peeler, remove the zest from the lemons (bright yellow skin only, no pith/white spongy portion around the actual lemon); set aside. Squeeze the juice from the lemons; set aside 1/2 cup. Freeze any leftovers.
Place the sugar in the bowl of your food processor and add the lemon zest on top. Pulse until the lemon zest appears grated and combines with the sugar.
Add the butter and sugar-lemon zest mixture to the bowl of your electric mixer fitted with the paddle attachment. Beat on medium speed until the sugar breaks down, about 4 minutes.
Add the eggs, one at a time, mixing on medium speed until thoroughly incorporated after each addition.
Add the 1/2 cup of lemon juice and salt; mix on low speed just until combined.
Transfer the gluten free lemon curd to a 2-quart saucepan and cook over medium-low heat, stirring constantly, until thick and the curd coats the back of a spoon, about 10 minutes. (You should be able to draw a line with your fingernail in back of a wooden spoon that remains.)
Pour the lemon curd into a container, cover with plastic wrap directly on top of the curd. and refrigerate until ready to serve/use. If using in a prebaked pie shell, pour into the shell and refrigerate until set. For parbaked (partially baked) pie or tart crusts, pour into the crust and bake until set and lightly golden brown or according to the instructions.