Crack eggs into medium-sized microwave-safe bowl. Whisk in sugar, lemon juice, lemon zest, and salt. Set timer for 10 minutes and allow mixture to rest for sugar to fully dissolve.
After 10 minutes, whisk lemon mixture vigorously. With clean hands, break butter into small chunks and add to bowl. Whisk again and place in microwave for one minute.
Remove lemon mixture from microwave and whisk well. Return to microwave and continue to cook in one minute increments, whisking in between until curd is thick along the edges of the bowl, about 4 to 5 minutes depending on individual microwave power. Whisk once more and cook 30 seconds longer in microwave.
Pour lemon curd into a shallow baking dish. Lay a piece of plastic wrap on top of curd and squish plastic gently and evenly across the surface of the curd to prevent skin forming as curd cools.
Cool curd to room temperature, then place in refrigerator for a minimum of two hours to set. Remove plastic wrap and spoon curd into a jar or container with a tight fitting lid.