The high heat of the fire brings out the natural sugars in vegetables so they actually retain more of their flavor, vitamins and minerals than they do when cooked in water. As with meat and poultry, the heat of the grill seals in juices and heightens the natural flavors.
From asparagus to corn, radicchio to sweet potatoes, vegetables are right at home over a bed of hot coals. The best way to prepare vegetables is to select the freshest ones available and to cook them briefly and simply to conserve their distinctive flavors and nutrients. Grilling is the ideal method for doing just that, as you can watch them cooking, test them for doneness with a sharp knife or skewer (or better yet, taste!) and take them off the grill the moment they are done.
The key to grilling vegetables is to follow the seasons. Any vegetable that has been locally grown and allowed to ripen naturally will be markedly more flavorful than an underripe vegetable that has been flown in from afar. Local farmers' markets or roadside farmstands are ideal places to find vegetables in season. Second best is a specialty foods market that purchases their products from local growers. Better yet, grow your own vegetables in a garden plot in the backyard and harvest them just before you plan to cook them.
When choosing vegetables, seek out the freshest ones you can find. Look for vegetables that are plump, moist and unwrinkled. At a farmers' market or roadside stand, ask the farmer when the vegetables were picked, or ask him or her for a sample.
To prevent sticking and add flavor coat both the grill rack and the vegetables with oil before grilling. A grilling basket or grill screen is handy for cooking small vegetables that may fall through the spaces in the rack. Caramelization, which occurs when the natural sugars in vegetables come in contact with heat, adds another dimension of flavor.
Grilled vegetables can be eaten as is or seasoned simply with salt, pepper and fresh herbs, or perhaps a little citrus juice or minced garlic. They can be dressed up with aioli or hollandaise, added to pastas, salads, sauces and soups, and are terrific accompaniments to other grilled foods as part of an all-grilled meal.
Shopping for Vegetables
In-season vegetables grown close to home are best. Follow these guidelines when buying produce.
Medium-sized and fat stalks grill better than very thin spears, which can be bitter. Peeling the bottom third of the spears with a vegetable peeler will help them cook evenly.
Season: February through June.
Select heads of Belgian endive (chicory/witloof) and radicchio that are firm, fat and crisp, with tight, unblemished leaves.
Season: year-round; best in winter.
Carrots, Parsnips and Turnips
Choose smooth, firm vegetables that are free of cracks. Look for good color and a sweet smell. Small, mature vegetables have the best flavor.
Season: year-round; best in winter.
Look for firm ears with plump kernels and a lot of creamy colored silk; avoid ears with heavily soiled or slimy fringe. The husks should be bright green and appear moist, not dried out.
Season: May through September.
Look for evenly colored eggplants (aubergines) with shiny skin. Cut globe eggplants into slices for the grill; cook Asian (slender) eggplants whole or halved.
Season: year-round; peak in late summer.
Choose fresh bulbs that are smooth and tightly layered with no cracks or bruises. White and pale green, rounded bulbs tend to be more succulent than yellow or thin ones. Grocers sometimes incorrectly label fennel as sweet anise.
Season: year-round; peak from late fall through winter.
Look for mushrooms with relatively clean, firm caps. For portobellos, choose those that are evenly sized and have gills that appear clean, dry and distinct.
Season: year-round; best in late summer and early fall.
Look for onions that are firm with smooth, dry skins. Avoid any with soft spots, particularly at the stem end; green shoots; moldy areas; or moist, wrinkled skins. In the spring, seek out sweet onions such as Maui, Vidalia or Walla Walla.
Season: year-round; sweet varieties in spring and late summer.
Look for peppers (capsicums) and chilies with smooth skin, as they will be easier to char on the grill than gnarled or grooved peppers. Thin-skinned varieties need a gentler touch so that they don't develop holes while grilling from too-high heat.
Season: year-round; best late summer through fall.
Potatoes and Sweet Potatoes
Look for firm, unblemished tubers that are not wrinkled, tinged with green or cracked. Avoid potatoes that have sprouted buds.
Season: year-round; new potatoes best in spring; sweet potatoes best in fall and winter.
Select zucchini (courgettes), yellow crooknecks, pattypans and other summer squashes that are mature enough to have full flavor yet small enough to be tender and free of large seeds.
Season: year-round; best June through September.
Select tomatoes only in season, and make sure they are firm but ripe. Heirloom varieties are particularly flavorful. Never store tomatoes in the refrigerator or they will become mealy. A sunny windowsill is a good place to store underripe tomatoes.
Season: June through September.
Look for firm, unblemished squashes that feel heavy for their size.
Season: some varieties available year-round; widest selection in fall and winter.
Testing Vegetables for Doneness
Piercing a vegetable with a skewer or the tip of a knife will give you some idea of whether or not they are done. However, the best way to test a vegetable for doneness it to cut off a piece and eat it. Some vegetables, such as asparagus and fennel, are most satisfying when tender-crisp, which means tender when you first bite into them and crunchy at the center. Other vegetables, such as eggplants (aubergines) and mushrooms, should be cooked until soft throughout. Follow the doneness clues in the recipes, or cook until they are done to your liking.
Adapted from Williams-Sonoma Essentials of Grilling, Denis Kelly, Melanie Barnard, Barbara Grunes & Michael McLaughlin, (Oxmoor House, 2006).