Preheat oven to 450*

Toss eggplant, bell peppers, onion, and garlic with olive oil, salt, and pepper on a large sheet pan. Roast for 40 minutes, until browned, turning.

Cook orzo in boiling salted water for 7-9 minutes, until tender. Drain and transfer to a large serving bowl. Add the roasted vegetables to the pasta, scraping all liquid and seasonings from pan into bowl.

For dressing, combine ingredients and poor into pasta and vegetables. Let cool at room temperature, then add scallions, pine nuts, feta, and basil. Serve at room temperature.