Heat the oven to 250° C / 500° F and maintain the temperature.
Puncture the eggplant (aubergine) in a few spots, using a toothpick or bamboo skewer. Rub the eggplants with olive oil and place on a sheet pan. Place peppers and onions cut side down, on another sheet pan. Roast all vegetables for 10 minutes. Turn vegetables over and roast for another 10 minutes, or until eggplants are tender. Remove vegetables from oven and cover with foil.
Allow the vegetables to steam until cool enough to handle. Peel and seed the peppers, but do not rinse. Cut six of the pepper halves lengthwise then in half again (giving you 12 large quarters) and place in a mixing bowl. Remove 24 of the largest leaves of onion, discard and dry onion leaves. Add to the bowl of pepper pieces. Coarsely chop remaining onion and place in baking dish.
Cut the remaining pepper halves into 1⁄4 – 1⁄2 inch pieces and place in the baking dish with the onions. Split the eggplants lengthwise and scrape the flesh from the skins. Discard the skins. Coarsely chop the flesh and add it to the baking dish. Whisk the 7 tablespoon olive oil, salt, black pepper, lemon juice, garlic to make a dressing. Add all but 2 tablespoons of the dressing plus 1 tablespoon of the parsley to the baking dish, tossing well to combine with the chopped vegetables. Place the baking dish in the oven for 15 minutes. Remove, and let the vegetable mixture come to room temperature.
To serve, mound the vegetable mixture in the centre of a serving plate. Toss the large pepper and onion pieces in the mixing bowl with the remaining 2 tablespoons of dressing.
Scatter with remaining 2 tablespoons of chopped parsley and serve.