1. Cook quinoa: In a pot, bring 2 cups of water to a boil. Add quinoa, reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let it sit for 5 minutes, then fluff with a fork.
2. Grill vegetables: Preheat grill to medium-high. Toss zucchini, bell peppers, and red onion with 1 tablespoon olive oil, salt, and pepper. Grill for 5-7 minutes until tender and slightly charred.
3. Assemble salad: In a large mixing bowl, combine cooked quinoa, grilled vegetables, cherry tomatoes, parsley, and lemon juice. Drizzle with remaining olive oil, toss well, and serve.