1. Preheat grill pan over medium-high heat. Combine first 4 ingredients in a bowl; toss well to coat. Arrange zucchini in a single layer in pan; grill 4 minutes, turning after 2 minutes.
2. Combine parsley, mint, lemon rind, olive oil, and minced garlic. Divide zucchini evenly among 4 plates; top evenly with gremolata.