"People in Washington eat outside a lot," said a new arrival, encountering her third barbecue in as many weeks. That they do and, apparently, that they have for some time.

In 1809 Washington Irving wrote he "Engaged in great 'barbecue,' a kind of festivity and carouse much practiced in Merryland," though, in those days, people usually went whole-hog -- or whole-ox -- when they set up the spit.

Nowadays, it's hamburgers (steaks for those who can afford them,) chicken and ribs, which is a pity since there are many other things which respond happily to grilling.

Fish, for instance, particularly if you have one of those little hinged grills people used to use over campfires. You might cook a rockfish in the Mediterranean manner, stuffing it with sticks of dried fennel, painting it with olive oil and grilling it on each side about seven minutes. For a fancy finish, remove the fish to a fireproof platter piled with dried fennel stalks, and pour flaming brandy on top. The brandy will ignite the fennel, which will further flavor the fish. (Fennel, if you have none in your garden, should be available come September from Hudson Brothers greengrocers in the Georgetown Market, 3206 Grace St. NW.)

Many people bury baking potatoes in the coals, but food writer Leslie Land suggests grilling sweet potatoes which have first been cut into cubes and steamed until barely tender. She places them on skewers, coats them with melted butter and cooks them over medium-hot coals, basting frequently with more butter. In about 15 minutes, the potatoes are crisp and carmelized, ready to be served with coarse salt.

More exotic would be to have a parillada , an Argentinian barbecue, which, in addition to featuring cuts of meat not usually available here, begins with grilled sausages and includes sweetbreads, intestines, and bull fry (what, out West, they call prairie oysters). The grilled meats are served with sauce Chimichurri: oil, vinegar, parsley, garlic, ground red pepper and salt. Although the meat is not sauced before grilling, in some places it is basted with brine.

Osmar Leguizamon of El Chapparral, 1737 Wilson Blvd. in Arlington (527-3388), is a butcher who cuts meats in the Argentine manner and will tell you how to cook them. He also is a chef and will do a whole parrillada for you. Prices vary according to the number of people and what is to be served.