Preheat the broiler. Bring 6 cups water to a boil and add 1 tsp salt. Slice the potatoes lengthwise and ½ inch thick, boil them for 5 minutes, and drain. Halve the peppers lengthwise, press to flatten them, then brush with vegetable oil. Broil, cut side down, on a baking sheet until blistered but not charred. When cool, remove the skins and cut the pieces in half. Set the over temperature at 350 F.

Coarsely chop the basil, cilantro, and garlic, then puree in food processor with the olive oil, cumin, and ½ tsp salt.

Toss all the vegetables with 1 tsp salt, some freshly ground pepper, and the herb mixture. Using your hands, rub the herb mixture into the vegetables, especially the eggplant, then add the chickpeas and toss once more. Transfer everything to an earthenware gratin dish. Rinse out the herb container with ½ cup water and pour it over all. Cover the gratin dish tightly with foil and bake until tender, about 1 ½ hours. Remove the foil, brush the exposed vegetables with the juices, and bake for 20 minutes more. Let cool for at least 10 minutes before serving.