If the eggplant is young and fresh, there’s no need to peel it. Slice horizontally ¼-inch thick. Sprinkle with salt on both sides and set aside for 20 minutes. Trim tops of zucchini and slice horizontally, ¼-inch thick. Heat grill. Gently squeeze eggplant and discard liquid. Lay strips across grill and cook over medium heat, turning once, about 8-10 minutes total. Grill zucchini, turning once, about 4-5 minutes. Grill whole peppers and tomatoes until skins are completely charred. Place in paper bag and close top, or place in bowl and cover with plastic wrap. When cool enough to handle, peel off skin. Add to bowl with other vegetables. Season with salt and pepper and drizzle with olive oil. Toss with basil and serve.