Toss the zucchini, cherry peppers, carrot and celery with 1 tablespoon salt in a colander. Let drain 30 minutes, then pat dry with paper towels. Transfer to a bowl.
Bring 1 1/2 cups water, the vinegar, sugar, 2 tablespoons salt, the thyme sprigs, garlic, coriander seeds, peppercorns and cloves to a simmer in a medium saucepan and cook 5 minutes. Pour over the zucchini mixture; let cool. Discard the thyme sprigs. Refrigerate overnight or up to 2 weeks.