Preparing vegetables on the stovetop is quick and easy, whether you prefer stir-frying or simple boiling and steaming. These are fine and versatile cooking methods, but they do little to emphasize the vegetables' own flavors. If that's your focus, consider roasting your vegetables instead. The oven's dry heat caramelizes the vegetables' natural sugars, creating new and complex flavor compounds, and cooks the veggies without sapping them of flavor or water-soluble nutrients.
Many delicate vegetables, which might otherwise be steamed or stir-fried, take on a very different character when you roast them instead. Asparagus spears, or florets of broccoli or cauliflower, are good examples. Prepare your asparagus spears by snapping off the woody ends of their stems, and by peeling the lower half of each stem if you wish. For broccoli or cauliflower, separate the heads into bite-sized florets and blanch them for a minute or 2 in boiling water. Drain them thoroughly before proceeding. Toss the vegetables with a small amount of oil, and arrange them in a single layer on a parchment-lined baking sheet. Sprinkle them lightly with coarse salt, and roast them at 450 to 475 degrees Fahrenheit until they begin to caramelize and darken at the edges, roughly 10 to 12 minutes.
For larger or denser vegetables, you'll need to adjust your technique slightly. These include starchy vegetables such as potatoes, sweet potatoes and squashes, as well as softer and moister vegetables, including fennel and radicchio. Bulbs of fennel and heads of radicchio should be cut lengthwise into quarters or thick wedges, and lightly oiled. Cut starchy vegetables into wedges, cubes or -- in the case of squash -- thick half-moon slices. Large pieces yield a slightly crisp, caramelized exterior with a soft and creamy interior; small pieces have more of a french-fry texture. Roast the oiled vegetables at 450 F until they're tender and caramelized. The exact time varies with the size of your pieces.
Hard Root Vegetables
Hard root vegetables such as carrots, beets, parsnips and rutabagas take the longest to roast, but, in many ways, they are the quintessential roasted vegetable. They're all rich in natural sugars, with sweet and earthy flavors that are enhanced and concentrated by roasting. Peel the vegetables if needed -- carrots and parsnips can simply be washed, if you prefer -- and slice or dice them. Toss them with oil, and arrange them in a single layer on your baking sheet. Roast the vegetables at 450 F until they're tender and caramelized. If they brown too quickly and threaten to char, turn the heat down and finish them at 350 F.
Tweaks and Tips
Although roasting emphasizes the vegetables' own flavors, there's plenty of opportunity for creative cooks to tweak their taste. Add a splash of balsamic vinegar or pomegranate syrup when you toss the vegetables in oil, for a sweet-and-tangy note that complements the vegetables' own sweetness. Opting for maple syrup, brown sugar or honey emphasizes the sweetness instead, forming a glaze as the vegetables cook. Warm spices such as ginger and nutmeg emphasize the natural sweetness of the vegetables, while the aromatic, woodsy camphor notes of rosemary or fresh sage make them more savory.