Preheat oven to 425 degrees. with racks on top and bottom. On a rimmed baking sheet, toss together tomatoes, carrots, garlic, 2 tablespoons oil, 1 teaspoon salt, and 1/4 teaspoon pepper. Spread in a single layer, with tomatoes cut sides down.
On another rimmed baking sheet, toss together eggplant, chickpeas, curry powder, remaining 2 tablespoons oil, 1 teaspoon salt, and 1/4 teaspoon pepper. Spread in a single layer. Place both sheets in oven (tomato mixture on top rack). Roast until tender, tossing mixtures halfway through, about 45 minutes.
Using tongs, peel off and discard tomato skins. Puree tomato mixture (including juices) in a blender or food processor until smooth. Transfer to a large pot. Stir in eggplant mixture; thin with 3 to 4 cups water. Bring to a simmer over medium heat. Season with salt and pepper. Serve, sprinkled with cilantro; garnish with bread, if desired.
To freeze this dish, omit the cilantro; let the soup cool completely before transferring to storage containers. Freeze up to three months. To cook: Defrost overnight in the refrigerator (or use the microwave). Reheat over medium-low heat; thin with more water, if desired. Sprinkle with cilantro just before serving.