Summer is the season for grilling, as we all know, but don't limit yourself to meat. Seasonal vegetables are gorgeous on the grill, too. The intense heat of the grill concentrates their flavors and adds a smoky undertone that is very appealing.
The main tip for grilling vegetables of whatever kind is to keep the fire moderate (or, for delicate vegetables, low) and to be vigilant. A little charring is nice, but too much renders most vegetables rather bitter, so be vigilant as you cook. Vegetables cook at different rates, with harder ones like whole onions taking longer than tender or leafy vegetables, so if you want to serve mixed grilled vegetables, start the longer cooking ones first, then add vegetables on the grill that take less time.
A generous drizzle of olive oil while their still hot off the grill, and a nice sprinkling of salt and pepper is all you need, and you'll be good to go. I like to serve grilled vegetables with crusty bread and some summer cheeses (mozzarella or provolone, or both) although they are fantastic with softer, aged cheeses. (Brie is particularly nice.) Serve it all accompanied crisp, cold white wine and enjoy!
Here are some of my favorite vegetables for grilling and some tips on technique:
Eggplant might be my all-time favorite. To prepare them for grilling, trim their tops and bottoms and cut them either into rounds or lengthwise into long slices. No need to peel them; in fact, the skin helps hold them together. Brush them with olive oil on both sides. Grill then over a moderate flame until they are lightly spottled on both sides. They cook fairly quickly so be vigilant, as they tend to go from pleasantly caramelized to bitterly burnt in no time.
In the alternative, you can grill smaller eggplants whole, or cut into half lengthwise. They will take much longer to cook (perhaps 20-30 minutes depending on their size). Scoop out their flesh and mash it up with plentiful olive oil, salt, pepper, some chopped parsley and finely chopped garlic. Serve this 'eggplant caviar' separately, in a bowl, with some pita bread or toast.
Zucchini are a close second to eggplant in my grilling hall of fame. To prepare them for grilling, trim off both ends and then cut them lengthwise into slices or (as I prefer) wedges. Grill them over moderate heat until they are soft and spottled on all sides. Try to find smaller zucchini with smooth skins, which taste sweeter and are much more tender.
Peppers, red, green or yellow as you prefer, also benefit greatly from grilling, although their skins develop a bitter taste when charred. I like to grill them whole, then let me rest in a plastic bag for a few minutes to cool. After that, it's short work to remove the skins and seeds. You then cut them up into strips and season with garlic, salt, pepper and olive oil to serve. (They are even better when made ahead.) But sometimes I get lazy and just cut them into wedges and grill them that way, served with a generous sprinkling of salt and a good pour of olive oil on top. Still very good.
Tomatoes are fantastic on the grill. My favorite method is to cut them into halves horizontally, then top their exposed flesh with a mixture of finely chopped parsley and garlic, and top with lots of salt and pepper and drizzle with olive oil. Grill them lightly on a vegetable grate and remove as soon as their skins begin to char a bit.
Green onions are wonderful on the grill. Just trim off their root ends and about half of their green tops. Being small, they will easily fall between the grates into the fire, but, to avoid this, you can either use a special vegetable grate or skewer a few of them together. These babies cook very quickly.
Whole yellow, red or white onions are also very nice on the grill. Try to find the smaller ones to save on grilling time, but even so they will take a bit longer than other vegetables (at least 10-15 minutes). Keep their skins on and wrap them individually in aluminum foil, drizzled with a bit of olive, salt and pepper before closing your 'packet'. Then place them on the grill. The fire should be nice and hot, but you should preferably grill them over indirect heat (i.e., not directly over the flame). Let me cool off for a few minutes before serving. Their skins will probably be charred but their flesh will be soft and unctuously delicious.
Slim carrots are surprisingly nice on the grill. They take a bit longer than other vegetables, so grill them over a gentle flame.
Although not typical summer vegetables, radicchio and Belgian endive are also great on the grill, cut into halves or wedges. Both (but especially the radicchio) will cook quite fast, and burn easily, so make sure your flame is gentle. (On a gas grill, use a 'low' flame.)
Fennel is another 'out of season' vegetable that is nevertheless very nice on the grill. You just trim off their stems and slice them vertically (the stem end keeps the slices whole). Then grill them lightly on both sides and serve drizzled with olive oil and a sprinking of salt and pepper.