Lemon Syrup

Step 1
Heat lemon juice, water, sugar, lemon zest, and cornstarch in a pot over medium heat. Simmer until thickened, about 5 minutes; remove from heat.

Step 2
Sterilize the jars and lids in boiling water for at least 5 minutes.

Step 3
Pour the lemon syrup into the hot, sterilized jars, filling the jars to within 1/4 inch of the top.

Step 4
Run a knife or a thin spatula around the insides of the jars after they have been filled to remove any air bubbles.

Step 5
Wipe the rims of the jars with a moist paper towel to remove any food residue. Top with lids, and screw on rings.

Step 6
Process jars in boiling water in a large pot for 10 minutes; remove jars from pot and allow to cool.

Step 7
Once cool, press the top of each lid with a finger, ensuring that the seal is tight.