3 large eggs
1/2 cup freshly squeezed lemon juice
1/2 cup granulated sugar
zest of 3-4 lemons
1/4 cup butter, unsalted
1/8 teaspoon salt
Place the sugar in a medium sized pot, and over it zest the lemons. Rub the sugar and zest together between your fingers to release the oils.
Pour the lemon juice into the pot and gently stir it into the sugar.
In another bowl, add the eggs and salt. Beat very well with a fork or whisk. Pour the eggs into the sugar and whisk again.
Set the pot over low heat. Cook, stirring constantly until the curd thickens and registers 170 F on an instant read thermometer (or until it coats a rubber spatula).
Cut the butter into 1/4 inch slices and set it in a bowl. Place a sieve over it. Pour curd through the sieve into the butter to remove zest and any egg bits. Stir until butter is thoroughly melted.
Serve immediately.
Can be frozen for up to 2 months.