Roasting vegetables is a healthy way to serve them because it doesn't require large amounts of oil or butter to do. However, cooking vegetables at very high temperatures can sometime result in nutrient loss, but doing it the right way preserves the nutrition of the vegetables without sacrificing flavor. According to Fit Day, storing vegetables in the refrigerator until ready to cook them should help retain nutrients. Vegetables are a good source of fiber, vitamins, minerals and antioxidants so they should be part of a healthy and balanced diet. Roasting them often brings out the sweetness, making them more palatable for people who don't really care for vegetables.
Preheat the oven to 400 degrees F. You can go all the way up to 500 degrees, but the higher the temperature, the more quickly the vegetables begin to lose their nutrients.
Cut the vegetables into chunks. Vegetables that roast well include potatoes, bell peppers, onions, asparagus, beets, broccoli, brussels sprouts, cauliflower, squash and carrots. Group vegetables that are similar in hardness together because otherwise one vegetable may be completely roasted while others are still cooking. For example, onions and bell peppers cook to doneness at about the same rate.
Coat the vegetables. Spray a cookie sheet with cooking spray. Place the cut vegetables in a bowl and drizzle with cooking oil. Stir the vegetables to make sure they are evenly coated with the oil and pour them on the cooking sheet. Lightly mist the top with cooking spray. The spray contains less calories than the oil, allowing you to get browned and crispy vegetables without a huge amount of added calories and fat.
Season the vegetables. This can be as simple as sprinkling them with salt and pepper. Or you can use herbs like rosemary or thyme to create new flavors. Garlic and seasoning salt also add flavor. Lemon juice or orange zest gives the vegetables a refreshing flavor while chili powder or cayenne pepper adds a little heat. Experiment with flavors until you find one you like.
Roast the vegetables for about half an hour. Overcooking the vegetables results in nutrient loss, so be sure to remove them from the oven as soon as they are finished. They should be firm, but soft enough that they are no longer raw and so they can be easily chewed. Some vegetables may take a little longer or a little less time to cook so watch them carefully. Use a spatula to turn the vegetables about halfway through cooking to achieve an even degree of doneness.