Wash and dry the lemons. Carefully remove the zest from the lemons, using a serrated vegetable peeler. You want to remove only the bright yellow part, not the bitter white pith underneath.
Put the sugar and the zest in a food processor and pulse to combine. Then process until the zest is fully incorporated into the sugar. This will take under a minute. Take a look, the sugar should be fragrant, moist, and pale yellow. If you see chunks of zest, process a little longer. Fine bits of zest are ok.
Use your sugar in your recipe right away for freshest flavor, or store in a zip lock freezer bag in the refrigerator and use promptly.
https://theviewfromgreatisland.com/how-to-make-lemon-sugar-recipe/ June 17, 2019