1. In a 12- by 17-inch roasting pan, combine carrots, cauliflower, broccoli, bell peppers, and artichoke hearts with their marinade.
2. Roast in a 400° oven, stirring every 15 minutes, until carrots are tender to bite, 50 to 60 minutes.
3. In a large bowl, combine lemon juice, olive oil, vinegar, mustard, and garlic. Scrape in vegetables, add olives, and stir to coat. Season to taste with salt and pepper.