GRILLING THE `GOOD BURGER' GUYS; NICKELODEON CAN'T CONTAIN POPULAR DUO KENAN & KEL.

Byline: Janet Weeks Daily News Staff Writer

It's lunchtime at the swank Mondrian hotel restaurant on West Hollywood's famed Sunset Strip, and rising teen superstars Kenan Thompson and Kel Mitchell are hungry.

``Garcon, biscuits!'' Thompson, a 19-year-old Atlanta native, shouts as he saunters into the artsy, beige-on-beige-on-beige foyer.

Biscuits? At the Mondrian?

The two sit down at a table with a sweeping view of Los Angeles. The tony Mondrian is far removed from the fast-food joints where they have spent much of the last few weeks promoting their first feature film, ``Good Burger.'' In fact, the Mondrian was selected for lunch to give the teens a break from a steady diet of hamburgers.

But the menu is a problem. It's entirely in Italian. And even recognizable offerings - raviolis, for example - are upscale, stuffed with lobster instead of meat or cheese.

Mitchell, 18, finally puts down the menu and tries to negotiate with the heavily accented waiter.

How about spaghetti and sausage? The waiter checks with the kitchen. There is no sausage at the Mondrian. The waiter suggests veal. Mitchell wrinkles his nose. Thompson steps in. How about a milkshake? Again, the waiter checks with the kitchen. There are no milkshakes at the Mondrian. The waiter suggests a hamburger.

A hamburger? Oh, you can take the kids out of the burger joint but ...

Opening Friday, ``Good Burger'' marks another expansion in the budding cottage industry that Thompson and Mitchell are fast becoming. If you've never heard of Kenan and Kel, you probably don't have kids.

The duo are stars of two of the most popular shows on the cable network Nickelodeon - their own ``Kenan and Kel'' and the popular Saturday night variety program ``All That.''

Cookin' up comedy

``Good Burger,'' a goofy comedy set in the world of patty flippers and french-fry servers, is a spinoff of an ``All That'' sketch.

Both the sketch and the movie star Mitchell as Ed, a braid-wearing airhead who not only works at the small, family-owned Good Burger restaurant, but lives for Good Burger.

Anyone who has seen Ed is not likely to forget him or his trademark sing-song greeting to customers: ``Welcome to Good Burger, home of the Good Burger. Can I take your order?''

Thompson plays Dexter, a high school student who gets a summer job at Good Burger to pay off a debt. He hates the job, and, at first, tries to rip off hapless Ed. In the end, he and Ed team up to save Good Burger from an evil plot hatched by the restaurant's competition, Mondo Burger.

``Good Burger'' caps several years of team comedy for Mitchell and Thompson. When asked how they first came together as a duo, Thompson says: ``Actually, it's a funny story. Would you like to hear it? A'right. Let's get comfortable. It all started about four years ago ...''

At that, Mitchell makes a high-pitched, ``Twilight Zone''-esque ``di-di-di-di'' that signals a flashback.

``The chemistry between me and him happened when they put us together in an `All That' sketch called `Mavis and Clavis,' '' Thompson continues. In the sketch, the two play senior citizen hecklers talking back to the ``All That'' cast onstage. Midsketch, the two began improvising. The results cracked up the room.

Says Mitchell: ``It was like, `Hey. This kid acts like me.' From there on out, it was all magic. We were laughing at each other the whole time.''

``All That'' director Brian Robbins, who also directed ``Good Burger,'' remembers it this way:

``The chemistry between them - they had us dying on the first run-through. They had these brain waves. It was magic. After we did the first season of `All That,' we all knew that these guys had to have their own show.''

Different strokes

The two play off each other because, as comedians, they are opposites, says Robbins. Mitchell excels at physical humor while Thompson's comedy is of the verbal variety.

Robbins discovered the two during separate auditions for ``All That.'' Mitchell was hired after a very big casting call in Chicago - and almost wasn't considered.

``It was the worst audition,'' Robbins says of the kids who performed for them in the Windy City. ``We saw everything but what we were looking for. We were packing up to leave, and they said there's one more kid outside. It was Kel. He had thick glasses on and he was real nervous. He fumbled his monologue.

``But there was something about him. I said `Forget the monologue. Can you imitate a preacher? How about Michael Jackson?' And we hired him right on the spot.''

Ed, the ``Good Burger'' guy, was invented at the same audition, Mitchell remembers.

``They wanted me to put a wrestler and a surfer together. And that's how it happened. All of a sudden, it just came out like that.''

Thompson was already a veteran of the business when he came to Robbins' attention. He had previously appeared in the films ``D2: The Mighty Ducks'' and ``Heavyweights'' and had been a movie critic for CNN's ``Real News for Kids.''

``Kenan has this old soul, and I just fell in love with him,'' Robbins says.

Thompson was the last actor cast for ``All That,'' arriving at Nickelodeon Studios in Orlando, Fla., after the others had been introduced with two parties.

``Everybody knew each other. But I missed all of this,'' says Thompson. ``So on the way to (studio) school in the van, I didn't talk to anybody. I was all in the corner acting like a little geek doing my homework.''

As soon as he began working with Mitchell, he knew the two were onto something good, Thompson says. And they hope to continue the pairing with other films and shows.

``We've already made history, being as young as we are and being African-Americans and having our own show and film,'' says Mitchell. ``So we might as well make more history by staying together for a long time.''

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3 Photos

Photo: (1--Cover--color) `Burger Time'

Nickelodeon's Denan and Kel poised to take a big bite of the entertainment corld woth their new film

(2) Kel Mitchell, 18, left, and Kenan Thompson, 19, are taking two of the characters they play on Nickelodeon's ``All That'' to the big screen in ``Good Burger,'' the duo's first film together.

Phil McCarten/Daily News

(3) In ``Good Burger,'' Ed (Mitchell), left, loves working at his family's hamburger joint, while Dexter (Thompson) is less enthusiastic.