- 2 cups apple cider vinegar
- 1/2 cup (packed) brown sugar
- 10 whole cloves
- 3 whole star anise pods
- 2 tablespoons kosher salt
- 1 tablespoon dried mustard powder
- 1 tablespoon mustard seeds
- 1/2 teaspoon black peppercorns
- 2 medium yellow squash (about 1/2 pound), thinly sliced crosswise
- Bring vinegar, brown sugar, cloves, star anise, salt, mustard powder, mustard seeds, peppercorns, and 2 cups water to a boil in a medium pot over high heat, stirring occasionally. Reduce heat to medium-low and simmer 10 minutes.
- Place squash in a heatproof resealable container or jar (divide among several containers if necessary). Pour hot brining liquid over squash. Let cool to room temperature, then cover and chill at least 2 hours before serving.