You can blanch vegetables a day ahead and refrigerate in airtight containers.
- 3 red or yellow bell peppers
- Coarse salt and freshly ground pepper
- 12 medium, thin carrots (about 5 inches long), trimmed and peeled
- 2 medium yellow squash, trimmed, cut into 2-inch chunks, and cut diagonally in half
- 2 medium zucchini, trimmed, cut into 2-inch chunks, and cut diagonally in half
- 3 small fennel bulbs, trimmed and cut into 3/4-inch wedges or 1/2-inch-thick slices
- 2 small celery roots (about 12 ounces each), peeled, halved lengthwise, and cut crosswise into 3/4-inch-thick pieces
- 2 tablespoons coarsely chopped fresh thyme leaves
- 1/4 cup coarsely chopped fresh basil leaves
- 2 cloves garlic, finely chopped
- 1 cup extra-virgin olive oil
- 2 heads radicchio, halved through the stem if small, quartered if large, stem end left intact to hold leaves together
- 4 small tomatoes, halved crosswise
Place the peppers directly over the flame of a gas-stove burner on high heat or on a grill. Roast peppers, turning with tongs, until blackened all over. (Alternatively, broil peppers on a baking sheet, turning as each side becomes charred.) Transfer to a large bowl, and cover immediately with plastic wrap. Set aside to steam 15 minutes. Peel peppers; discard skin. Remove stems, seeds, and ribs; cut each pepper into 2-inch pieces.
Prepare an ice-water bath; set aside. Bring a large pot of water to a boil. Add 1 tablespoon salt. Add carrots; cook until tender, about 8 minutes. Using a slotted spoon, transfer to ice-water bath to stop cooking; transfer to kitchen or paper towels to drain completely. Repeat the process with squash, zucchini, fennel, and celery root. Squash and zucchini will take about 5 minutes; fennel and celery root will take about 8 minutes.
Preheat grill to medium (if you are using a charcoal grill, coals are ready when you can hold your hand 5 inches above grill for just 5 to 6 seconds). Whisk together thyme, basil, garlic, and oil in a small bowl; season with salt and pepper. Brush all of the vegetables with herb oil. Grill peppers and blanched vegetables until heated through and marked by grill, about 5 minutes for peppers, 8 to 10 minutes for blanched vegetables. Grill radicchio and tomatoes until cooked through, 8 to 10 minutes for tomatoes, 7 to 8 minutes for radicchio. Transfer to serving platters. Brush with remaining herb oil; season with salt. Serve warm or at room temperature.