Slice the eggplant and zucchini lengthwise into 1/4-inch thick strips and lightly sprinkle with salt. Let stand in a colander for about 1/4-hour until vegetables perspire. Rinse well and dry with a paper towel.
Meanwhile, remove outer skin from head of garlic and cut tops of cloves off. Brush garlic lightly with olive oil and place in the center of the cooking grate. Cook 45 minutes or until garlic is soft and cooked through. Remove from grill, remove garlic pulp, and set aside. Combine garlic with the olives, tomato, red pepper flakes, balsamic vinegar and Herbes de Provence in the bowl of a food processor. Lightly pulse with 1 teaspoon of olive oil, until mixture has combined and formed a paste.
Lightly brush or spray eggplant, zucchini, and bell peppers with olive oil and place in center of the cooking grate. Grill, for 4 to 6 minutes, turning once during cooking. Vegetables should be cooked through, but not limp. Just before serving, split rolls and place on cooking grate to toast. Assemble sandwiches by layering lettuce, grilled vegetables and goat cheese (if desired). Spread garlic-olive paste on top bun and season vegetables with salt and pepper.