Preheat the oven to 150 degrees F (165 degrees C), or the lowest setting you have.
Combine the lemon juice, apricot puree and sugar in a saucepan. Cook over medium heat until sugar has dissolved.
Cover an 11x17 inch pan or cookie sheet with a layer of plastic wrap. Pour the pureed fruit onto the plastic and spread evenly to within 1 inch of the edge.
Bake for 4 to 6 hours in the preheated oven, using a spoon or a pair of tongs to keep the door slightly ajar, or until the puree has dried and is no longer sticky. Once dry, you can cut it into strips and store in an airtight container.