Step 1

Stir white vinegar, rice vinegar, water, and sugar in a large saucepan over medium heat until sugar dissolves. Stir in ginger, cinnamon, salt, peppercorns, and cloves and bring to a boil. Add watermelon rinds and simmer 5 minutes, or until softened. Remove from heat and allow too cool for 30 minutes.

Step 2

Divide jalapeño slices (if using) between 2 (16-ounce) glass jars with lids. Once cooled 30 minutes, divide watermelon rinds and pickling liquid between the jars. Cover and chill in the refrigerator for up to 2 weeks. For the best flavor, chill at least 24 hours before serving.