Sweet-and-Spicy Bread-and-Butter Pickles

Ingredients in this Recipe

1 medium white onion (about 8 ounces), halved and thinly sliced (about 1 cup)
1 teaspoon whole mustard seeds
1/4 teaspoon crushed red pepper flakes or 3 dried hot chiles
1/4 teaspoon turmeric
2 1/4 cups sugar
2 cups ice cubes
2 heaping tablespoons coarse salt
2 pounds Kirby cucumbers or summer squashes, cut into 1/8 inch thick rounds (about 6 1/2 cups)
3 cups cider vinegar or distilled white vinegar
3/4 teaspoon celery seed
3/4 teaspoon whole black peppercorns

See Full Recipe at Martha Stewart