From How to Cook Everything Vegetarian by Mark Bittman. Roasted onions are delicious and easy to make in the oven; to keep them intact, try not to fuss with them as they roast. You can use any kinds of onion you like here, even sweet ones like Walla Walla or Vidalia, though these sweet varieties will be much softer when done. Serve the onions hot, warm, or at room temperature, garnished, if you like, with chopped herbs or nuts. And, as a bonus, you can use the leftovers as an alternative to raw onions in virtually any dish. Other vegetables you can use: large shallots, simply peeled and left whole.