This easy-to-make dessert sauce is delicious with gingerbread, pound cake, or poached pears. It will keep for a week, covered, in the refrigerator.
Place the sugar, cornstarch, and salt in a medium-size saucepan. Whisk to combine.
Combine the water and lemon juice, and add to the pan gradually, whisking to blend. Heat the mixture over medium heat, whisking constantly, until it thickens and becomes clear, 4 to 6 minutes.
Remove from the heat and add the lemon zest. Serve hot or transfer the sauce to a container and refrigerate, covered.