Preheat the oven to 400°. Spray a glass, 9x13-inch pan with nonstick cooking spray or line a baking dish with parchment paper.
In a large mixing bowl, combine the vegetables with the olive oil, salt, pepper, and herbs.
Transfer the vegetables to the prepared pan and roast for 30 to 45 minutes, until the vegetables are tender and slightly browned on the edges. (The timing will differ depending on what kinds of vegetables you use. If you just use broccoli, it will be done in a much shorter time.)
Slice evenly. Even sized cuts will make sure they roast evenly in the oven.
Group veggies by cooking time. Not all veggies will roast the same time. Cruciferous veggies (like brussel sprouts, broccoli, and cauliflower) will take less time (like 20-25 minutes) than your root veggies (like carrots, potatoes, parsnips, and turnips).
Use a high heat. We find that 400°F is the perfect oven roasting temperature.
Season well. Make sure to season your veggies well and before you cook them for the best flavor.