This is the best lemon curd recipe ever! I can use fresh or bottled juice and lime works as well. I love that it only needs one whole egg and doesn't make a huge batch! I will be making it again soon...
1/4 cup sugar
1 large egg
1/3 cup lemon juice
Mix these ingredients in a small heavy saucepan with a whisk.
Heat on medium heat while whisking constantly. It will become frothy. Keep cooking and whisking until it becomes thick and completely frothy. Test on the back of a metal spoon. If it coats the spoon and doesn't fill in the line made by your finger, it is done.
Remove from heat and immediately whisk in 4 Tablespoons of cold butter, one at a time, using the whisk.
Pour into bowl and chill.