Roasted eggplant soup has eggplant as its main ingredient, but you can of course add other vegetables to the roasting pan. You can add chopped vegetables like bell peppers, zucchini, and carrots to add flavor, texture, and color. Instead of flame-roasted tomatoes, you also have the option of using fresh tomatoes to roast with the eggplant. If you prefer to use canned tomatoes, you can substitute standard diced tomatoes for flame-grilling if you prefer.
You can also vary the spices in your soup. Experiment with different herbs such as thyme, oregano, and basil for different scents. Spice it up with smoked paprika, coriander, or curry powder for another flavor. If you like something spicy, add red pepper flakes or cayenne pepper.
I use a neutral vegetable broth as the base for the soup, but you can get a richer flavor by substituting chicken or beef broth for the vegetable broth. To increase the umami flavor, add a tablespoon of miso paste or add dried mushroom powder.