When bats swoop low in the glooming night, and street lamps cast pale glimmers on the sidewalks, it is the hour of the Tasty.

No longer an insignificant diner, it dominates the empty streets. Through the gathering gloom, its greasy siren call brings in the faithful: hordes of people whose only bond is a common craving for a nocturnal hamburger.

"It's not really the Tasty until midnight," says Michael J. Smitah at 11:30 p.m. Friday, deftly wiping the grease off the grill. There are three burgers sizzling and four people sitting in the restaurant. One is reading a book. "At midnight," says Smith, the Tasty "bursts open; it changes."

The customers range from "brilliant professors to brilliant street people, to overeducated idiots," Smith says. Taxi-drivers, waitresses, bartenders, students--he sees them all, he says. "And lots of kooks, lots."

"Some people you just naturally fall into a relationship with," he says. "And others you avoid like the plague."

At 12:10 a.m., Michael J. Smith's shift is over. He takes off his apron and hands it to Michael Smith, who works the early morning shift with Charles Drapeau. They have worked together for 16 years.

Maria Maritoni, a student at the Extension School, sits at the counter next to her four-year old son, Justin.

Justin perches serenely on a swivel-top stool, a wooly red scarf wrapped around his face. He lists his interests as "playing, rolling cars, and this"--he brandishes a crumpled package od Starburst candies.

"How are you doing, Justin?" asks Michael J. Smith, leaning over and giving him a kiss. on his way out. Justin smiles and licks a yellow lollipop.

A man with a guitar comes in. "Guys! Live music at the Tasty? Can we do it?" says Maritoni, turning around to greet him.

"When all the street musicians are done with their acts, they come in here," she explains.

Drapeau and Michael Smith, stacking burgers begind the counter, turn off the sound system. "Ladies and gentlemen, we're making an exception to the general rule," says Drapeau. "This will last five minutes." He turns back to the grill.

Maritoni sits on the window sill, singing "Bluejay Way," to guitar chords. The customers are mostly silent, holding their plates and listening to the music.

Michael Smith hands Justin a hot dog, covered with green pickle relish and mustard. Justin is displeased. "Why does it come with mustard?" he asks.

"Can we wire off the mustard?" Matteo Luccio asks Drapeau. "He doesn't like mustard." Drapeau hands him a knife and a napkin.