First trim and cut the watermelon rind. Cut off all the pink flesh and peel the dark green skin off too. Cut into cubes.

Add prepared watermelon to a heat-proof jar along with red pepper flakes, star anise, ginger, peppercorns, and IPA.

In a small saucepan, combine the vinegar, water, sugar, and salt. Bring to a simmer and stir until the salt and sugar are dissolved. Pour the liquid over the rind.

Let the liquid come to room temperature and then cover with a lid and keep refrigerated for up to 6 weeks.