Feel free to leave out the tomato paste, but I think it adds a wonderful meaty taste to many vegetarian dishes. I always buy tomato paste in a tube, so I can easily squeeze out just a tablespoon or two at a time.
Top the chili with your favorite chili toppings such as diced avocado, scallions, cilantro and nonfat Greek yogurt. I especially like the yogurt to boost the protein content.