Preheat oven to 425 degrees F. Toss the eggplant, bell peppers, onion, and garlic with the olive oil, salt, and pepper on a large baking sheet. Roast for 40 minutes, until browned, turning once with a spatula.
Meanwhile, cook the orzo in boiling salted water for 7 to 9 minutes, until tender. Drain and transfer to a large serving bowl.
Add roasted vegetables to the orzo, scraping all the liquid and seasonings from roasting pan into the pasta bowl.
For the dressing, combine lemon juice, olive oil, salt, and pepper and pour on orzo and vegetables. Cool to room temperature. Add the scallions, pignolis, feta, and basil. Check the seasonings; serve at room temperature. Makes 6 servings.