Unlike meats and poultry that are steeped in a marinade for hours to infuse flavor before cooking, roasted vegetables are often marinated after cooking. Because roasting softens the veggies, the marinate penetrates them easily, blending their natural flavors with the herbs and spices in the marinade. Raw root veggies, such as carrots and beets, may resist the marinade. Marinate softer veggies, such as zucchini and summer squash, either before or after roasting.
Choose a marinade with the desired herbs and spices, or make your own. Marinades contain an acidic liquid, such as lemon juice, vinegar or wine; an oil to coat the food; and herbs and spices for flavoring. Combine the oil with the vinegar or wine following a 2 to 1 ratio, or twice as much oil as acidic liquids. Add the herbs and spices, garlic or minced onion, and other flavorings. Whisk the ingredients together to make a quick marinade. Set the marinade aside.
Pare and cut the vegetables into uniform-sized sections to ensure even cooking. If you are roasting quick-cooking veggies, such as mushrooms or green beans, with longer cooking vegetables, such as carrots and rutabaga, cut the longer-cooking veggies into smaller chunks.
Preheat the oven to 450 degree Fahrenheit.
Toss the cut vegetables in enough oil to coat them. This prevents them from drying out during cooking and encourages the veggies to caramelize while roasting. When the natural starches and sugars in the veggies break down and combine with the oil, they brown and create sweet caramelized veggies.
Roast the veggies until they are fork tender and evenly browned, approximately 20 to 30 minutes. Turn the veggies when the bottoms brown to ensure even browning.
Remove quick-cooking veggies as soon as they are tender and set them aside. Allow slower-cooking veggies to continue roasting until they are evenly browned and tender.
Place the roasted vegetables in a glass or plastic bowl. Avoid metal containers, which may react to the acids in the marinade and produce off-flavors or discolor the veggies. Pour the marinade over the veggies and allow them to soak for an hour or more.
Reheat the veggies before serving, if desired, or serve them cold.