Bring 4 quarts water to boil. Add salt and pasta, stirring to prevent sticking. Cook until al dente, about 8 minutes.
Meanwhile, in large skillet, heat water or broth over medium heat. Add garlic, onion, and bell pepper and cook, stirring often, until soft, about 5 minutes. (Add extra water if necessary.) Add eggplant and tomatoes and cook, stirring often, until vegetables are tender and tomatoes release their juices. Season with salt and pepper.
Before draining pasta, scoop out half cup pasta water and reserve.
Drain pasta and transfer to serving bowl. Add vegetables to pasta. Add reserved pasta water to skillet and cook over high heat, stirring, until reduced slightly. Add to pasta and vegetables. Sprinkle with parmesan soy cheese (optional) and serve.