Balsamic Grilled Zucchini 1.Preheat grill for medium-low heat and lightly oil the grate. 2.Brush zucchini with olive oil. Sprinkle garlic powder, Italian seasoning, and salt over zucchini. 3.Cook on preheated grill until beginning to brown, 3-4 minutes per side. Brush balsamic vinegar over the zucchini and continue cooking 1 minute more. Serve immediately.