Heat oven to 425 degrees, and arrange two racks in the top and bottom thirds of the oven.

On one sheet pan, toss together onion slices, zucchini, ¼ cup oil, 3 thyme springs, 2 rosemary sprigs, 3 garlic cloves and ½ teaspoon salt.

On a second baking sheet, toss together eggplant, red peppers, ¼ cup oil, 3 thyme sprigs, 2 rosemary sprig, 3 garlic cloves and ¾ teaspoon salt.

Place one tray on the top rack, and a second on the bottom rack of the oven. Roast both for 40 minutes, stirring vegetables two or three times.

Add tomatoes to the baking sheet with eggplant and peppers, then continue to roast until the tomatoes burst and the zucchini becomes deeply golden brown, another 20 to 25 minutes. The vegetables will become very caramelized, and that’s a good thing, particularly with the zucchini and onion.

Transfer vegetables to a serving platter, drizzle with a little more oil and squeeze juice from the one of the lemon wedges over the top. Garnish with basil leaves. Serve hot or warm, with more lemon wedges on the side.