Preheat oven to 475°F. Place first 5 ingredients in large bowl. Add drained artichoke hearts, 1/4 cup reserved artichoke liquid, and balsamic vinegar. Season with salt and pepper; toss well. Arrange vegetables in roasting pan. Roast until tender, stirring occasionally, about 30 minutes.
Combine parsley, grapefruit peel, and garlic in medium bowl. Season gremolata to taste with salt and pepper. Transfer roasted vegetables to platter, sprinkle with gremolata, and serve.