Zucchini Refrigerator Pickles

Wash and thinly slice 2 medium zucchini and 1/2 small sweet onion. Pack the slices tightly into two clean 1-pint mason jars, distributing 2 smashed garlic cloves evenly between them.

In a small saucepan, combine 1 cup white vinegar, 1/2 cup water, 1/4 cup granulated sugar, 1 tablespoon kosher salt, 1 teaspoon mustard seeds, 1/2 teaspoon celery seed, and 1/4 teaspoon red pepper flakes.

Bring the liquid to a boil over medium-high heat. Stir constantly for about 3 minutes, or until the sugar and salt have completely dissolved into the brine.

Remove the saucepan from the heat and let it cool for 5 minutes. Carefully pour the warm brine over the zucchini and onions in the jars until fully submerged. Secure the lids tightly and refrigerate for at least 24 hours before serving.