Preheat oven to 350 degrees F. Using a bowl, combine the sugar, and salt, flour, and stir well until all flour has disappeared. Slowly add the half-and-half. Add the egg yolks, lemon juice, and grated zest. Gently fold in the beaten egg whites and pour mixture into a buttered 8 by 2-inch square pan. Set the pan inside a larger pan. Carefully pour hot water into the larger pan so that it reaches about 1-inch up the sides of the lemon curd pan. Be very careful not to get any of the water in the lemon curd pudding. Bake for 30 to 35 minutes or until golden brown. Serve warm or cold.