Put the saucier over low heat and whisk vigorously, moving the pan on and off the heat every 10 to 15 seconds, bringing the mixture to 140 to 145 degrees F, on an instant read thermometer, approximately 3 minutes. Add 1 piece of butter at a time, every 30 seconds, while continually whisking and moving the pan on and off the heat. Maintain temperature around 120 to 130 degrees F throughout the remainder of the cooking process. Once half of the butter, or 8 pieces have been added, add 1 tablespoon of lemon juice. Add the remaining 8 pieces of butter, 1 at a time, every 30 seconds while continuing to move the pan on and off the heat maintaining 120 to 130 degrees After the last piece of butter has been added, add the remaining 1 tablespoon of lemon juice and the remaining 1/4 teaspoon cayenne. Add the sugar and whisk for 1 to 2 minutes.