How to Make It
Light a grill. In a mortar, pound the halved garlic to a paste with 1 teaspoon of salt. Stir in 3 tablespoons of the olive oil and the lemon juice.
In a small skillet, cook the pine nuts over moderate heat until toasted, about 3 minutes.
Thread the onion slices onto two parallel 10-inch skewers. Put the eggplant, zucchini and yellow squash slices on 2 large rimmed baking sheets; brush both sides with olive oil and season with salt and pepper. Brush the bell peppers and lettuce with olive oil. Grill the vegetables over a medium hot fire, turning occasionally, until lightly charred and just tender. The onions will take about 5 minutes per side; the eggplant, zucchini and squash, about 3 minutes per side; the peppers, about 3 minutes on each of 4 sides; the lettuce wedges, about 1 minute per side. Scrape the charred skin from the peppers, discard the stems and seeds and cut into strips.
Put a lettuce wedge on each plate. Mound the vegetables on the lettuce and sprinkle with the cheese and toasted pine nuts. Pass the lemon vinaigrette at the table.
Steam helps loosen a pepper's charred skin from its flesh. To create steam, place the hot pepper in a bowl and cover with plastic wrap, or place in it a plastic bag and seal, then let sit for 5 minutes and remove. The skin should slip right off.