Prepare all the vegetables: Cut the eggplant into 3/4-inch / 2 cm thick half-slices, season well with salt and set aside for 30 minutes. After this time, pat dry with paper towels (salting the eggplant can be omitted, but it makes, in my opinion, frying and browning easier).
Cut the zucchini into ½-inch / 1.5 cm slices, then cut them in half or in quarters (depending on their size). Cut the peppers into ½-inch / 1 cm strips. Dice the onion, chop the garlic very finely.
Pour boiling water over the tomatoes, peel them and chop into ½-inch / 1.5 cm cubes.
Pan-fry the vegetables: In a very large pan, heat 2 tablespoons of oil over high heat.
Pan-fry the zucchini, eggplants and bell peppers in batches: place the vegetables in a single layer in a pan (they can’t be overcrowded) and cook for approx. 2 minutes on one side and one minute on the other. The vegetables should be browned but not cooked through and tender. Transfer the browned vegetables to a very large pot and repeat until all zucchini, eggplants and bell peppers are browned.
Reduce the heat under the pan, add the onions and spices (if using dried spices), cook for about 6 minutes, until translucent, add the garlic and cook for one more minute.
Stew the vegetables: Add the chopped tomatoes and spices (if using fresh ones), cook, stirring and scraping with a spatula the brown bits at the bottom of the pan, as soon as they combine with the sauce, pour the content of the pan into the pot.
Add approx. ¾ cup of water to the vegetables in the pot, lightly season with salt and pepper, bring to a boil, cover and simmer over low heat for about 20 minutes, stirring from time to time. Vegetables should be tender, but still retain their shape. Season to taste with salt and pepper, if necessary. Serve.