Instructions

• Bring a large pot of water to a boil. Cut the celery root, carrots, parsnips, and sweet potato into 1-inch pieces. (If the parsnips are very thick, cut them lengthwise in half and remove the hard core before cutting into pieces). Add the celery, carrots, and parsnips to the boiling water and cook for 2 minutes. Add the sweet potato and cook until the vegetables are partially cooked, 6 to 8 minutes more. Drain well and allow to completely cool.
• Prepare the grill for direct cooking over medium heat (350° to 400°F) and preheat a perforated grill pan for about 10 minutes.
  Prepare the grill for cooking over medium heat (400°F) and preheat a perforated grill pan for about 10 minutes.
• In a large bowl whisk the oil, rosemary, garlic, salt, and pepper. Add the vegetables to the bowl and turn to coat.
• Spread the vegetables in a single layer on the grill pan and grill over direct medium heat, with the lid closed, until lightly charred and quite tender, about 10 minutes, turning occasionally. Serve warm.
  Spread the vegetables in a single layer on the grill pan and grill over medium heat, with the lid closed, until lightly charred and quite tender, about 10 minutes, turning occasionally. Serve warm.