In a large glass jar or bowl that holds about 2 quarts, add the cilantro, garlic, peppercorns, coriander, red pepper flakes, zucchini, and onion. Set aside.
In a small saucepan over medium-high heat, bring vinegar, water, salt, and honey to a boil. Pour hot mixture over contents in the jar, pressing down on the vegetables so that brine covers them completely. Let cool on the counter to room temperature. Cover and refrigerate for at least 4 hours, or 2 days for maximum flavor.
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