Preheat the oven to 375 degrees.
Trim the ends of the zucchinis and cut them diagonally in ¾-inch-thick slices. (The slices will seem large, but they’ll shrink while they cook.) Cut the peppers lengthwise in 1½-inch-wide slices, discarding the core. Trim off the fennel stalks and cut the bulb through the core in 1-inch wedges. (Cutting through the core keeps the pieces intact.) Peel the onion and slice it in ¼-inch-thick rounds, leaving the slices intact.
Place the vegetables in groups on a sheet pan. Drizzle with the olive oil, add the garlic, and toss gently to be sure the vegetables are lightly coated with oil. Spread the vegetables in one layer on 2 sheet pans. (If they’re crowded, they’ll steam rather than roast.) Sprinkle with the salt and pepper and place the thyme sprigs on top. Roast for 15 minutes. Turn each piece and put the pans back in the oven for 5 to 10 minutes, until all the vegetables are crisp-tender. Sprinkle with extra salt and serve hot or at room temperature.
Copyright 2010, Barefoot Contessa How Easy is That? by Ina Garten, Clarkson Potter/Publishers, All Rights Reserved