Bring a large pot of lightly salted water to boil. Add orzo, and cook until al dente, about 8 to 10 minutes. Drain, and set aside.
Meanwhile, warm olive oil in a large skillet over medium heat. Stir in onion, garlic, and carrot, and cook for 2 minutes. Stir in zucchini, and cook for 2 minutes more. Pour in 1 tablespoon balsamic vinegar, and deglaze pan. Reduce heat to medium low, and season with salt and pepper. Add orzo to skillet, then stir in remaining 1 tablespoon balsamic vinegar and lemon juice.
