Cauliflower Chowchow

Name: Cauliflower Chowchow
Prep time: 30 minutes
Total time: 30 minutes
Yield: makes 1 quart
Ingredients: 4 cups 1/2' cauliflower florets (cut from 1 large head); Kosher salt; 1 cup apple cider vinegar; 2/3 cup finely chopped onion; 5 1/2 tablespoons sugar; 4 teaspoons yellow mustard seeds; 1 1/4 teaspoons (generous) dry mustard; 1 1/4 teaspoons (generous) celery seeds