Preheat an outdoor grill. Preheat an oven to 350°F/180°C.
Grill the eggplants, tomatoes, bell peppers and onions over a very hot fire, turning occasionally, until they are black on all sides, about 10 minutes.
Remove the vegetables from the grill and place in a 9x13-in. baking pan. Place in the oven and bake until soft. The eggplants, tomatoes and peppers will cook in about 20 minutes, the onions will take about 1 hour.
When the vegetables are done, place them in plastic bags and let them cool until they can be handled comfortably.
Core, seed and peel the peppers and slice into thin strips. Peel the eggplant and tear the flesh into thin strips. Peel and thinly slice the onions. Slip the tomatoes from their skins and quarter them.
Arrange the vegetables and olives on a large serving platter. Season with salt and pepper and drizzle with 2 Tbsp. olive oil. This can be done several hours ahead of time.
Combine the parsley and 2 cloves minced garlic and sprinkle over the vegetables. Toast the bread until golden.
Rub one side of each toast with a whole garlic clove and then brush with the remaining oil. Tuck the toast around the vegetables.