Prepare barbecue (medium-high heat). Blend vinaigrette and mint in small bowl for dressing. Cook orzo in medium saucepan of boiling salted water until just tender but still firm to bite; drain. Return orzo to same pan. Mix in 3 tablespoons dressing. Season with salt and pepper.
Thread bell pepper, eggplant and zucchini onto 4 metal skewers; brush with dressing. Grill vegetables until tender and just charred, turning and brushing often with dressing, about 12 minutes.
Divide orzo between 2 plates. Place vegetable skewers atop orzo. Sprinkle with cheese and serve.