Place sugar, lemon juice and 2 tbs of water in a medium saucepan. Over medium heat stir until combined and mixture starts to simmer. Cook for 4 to 6 minutes or until it starts to turn a golden colour remove from heat. Remember that sugar continues to cook after it is removed from the heat. Let cool slightly and add the set aside cream and salt. Mix and let sit. When nice and thick and gooey spoon over tarts.