Mastering the process of roasting vegetables will forever change your cooking. Never again will you have to look up a recipe for roasted sweet potato fries, or summer squash and tomatoes, or hearty winter veggies. Let’s take a look at the four basic components of roasting vegetables: oil, salt, seasonings, and temperature.
Unless you want to wind up with shriveled, dry, flavorless bits of burnt food, you need to toss your chopped veggies in ample oil. I recommend using extra virgin olive oil; it has the best flavor and can withstand temps up to around 400-450°F, which means it’s perfectly safe in the oven. How much oil you use depends on how much food you’re roasting. You want all of your food pieces to be coated lightly with oil, but not dripping. Aim for about 1 tablespoon of oil for every 1 to 1 ½ cups of chopped veggie.
Salt makes things taste good, and that alone should be reason to use it. But it’s especially important in roasting because it also draws moisture out of things—in other words, it helps to soften your foods as they cook, while keeping them moist. (If you roast your veggies without salting them before they go in the oven, they’ll likely come out drier, more “shriveled,” and less appetizing.) As usual, salt to your own taste, but figure at least ½ teaspoon of quality sea salt for every full baking sheet of veggies.
You may want your veggies to have more than simple olive oil and salt to give them a flavor boost (though, honestly, quality olive oil and proper salting are all it takes to make your roasted veggies taste just about perfect), and so you may want to call upon select herbs and spices to jazz things up. When to add the seasonings: before or after roasting? Depends on what you’re using. Default to this standby: Add dried spices and herbs before roasting (you can toss them with the veggies, salt, and oil), and add fresh herbs after roasting. The dried herbs and spices will release more essential oils and aromas in the hot oven, while the fresh herbs are best tossed into your veggies only when taken out of the oven.
The temperature you cook your veggies at has an impact on not only how fast they cook in the oven, but on how they cook in the oven. A lower temperature at, say 325-350°F will yield a slightly softer cooked vegetable, as there’s more time for the heat to permeate into and cook the inside of the chopped veggies.
Roasting at higher temps in the oven, say 400-475°F, will give you a more crusted, slightly caramelized result, but you have to be more careful that your foods don’t burn, as they’ll cook faster. Also, you’ll want to chop your vegetables slightly smaller here, as there’s less time for the heat to permeate all the way through each piece of food (again, since it’s at a higher heat, the outer part of the vegetables will start to burn faster).
Above all else, use your senses to guide your roasting. The prepped, chopped food should be visibly coated in oil, be well-salted, and should be allowed to cook at whatever temp you set the oven at until lightly browned and softened, stirring every 15 to 20 minutes. Adjust final seasonings, add fresh herbs and a splash of citrus or balsamic vinegar, and you’ve just mastered the art of the roasted veggie.