Cut the vegetables for grilling. Figure 1/3-inch thick slabs of zucchini, eggplant, potato, and onion. Cut bell peppers into quarters and remove seeds and stem. Lightly brush the vegetables with olive oil and season with salt and pepper.
Serve vegetables with crème fraiche.
Cut vegetables as follows, then coat lightly with olive oil, and season with salt and pepper before grilling:
Bell peppers -- cut in half, remove stem and seeds, cut each half into thirds
Zucchini -- slice lengthwise into 1/3-inch-thick slabs
Eggplant -- Cut into 1/3-inch-thick rounds
Onion -- Peel and cut into 1/3-inch-thick rounds