I'm a fool for truffles, and I'd kill for caviar, but in their absence -- and absent they usually are -- I'll happily settle for a steak-and-cheese sandwich. I'm addicted to these things, sometimes getting through three or four a week. I've tried giving them up. I've been in and out of rehab for years. But nothing seems to help, not even acupuncture. Which is why my doctor recently recommended the steak-and-cheese sandwich at Cafe Artiste (1601 West Main, 528-3704). "If you have to eat these things," he said, "at least eat a good one." And he's right. They are good. Called a po boy here, the sandwich's steak is shaved, the onions caramelized, and the cheese -- no meddling, please -- is the ever serviceable Kraft Swiss slices. And there's more: sauteed red and green peppers, and pan-fried potatoes with more garlic than Naples consumes in a week. If this be slumming, then I, for one, fully intend to slum on.