DESIGNER YEOHLEE TENG HAS ALWAYS had a cult fashion folowing. The audience at one of her unpretentious shows speaks volumes about her work and those who wear it. Scanning the front row, you'll be sure to see faces like Museum of Modern Art doyennes Agnes Gund and Paola Antonelli, Vogue's Sally Singer, and the Met Costume Institute's Harold Koda. And you can bet that these serious folks are not there just because she is the "next big thing." They admire the designs that Malaysian-born Teng has been creating consistently for years, infusing modernism with beauty, precision with fluency, and luxury with wearability. "When I came to New York, I had no preconceived ideas," says Teng. "And coming from the tropics, I never wore heavy clothes, so this gave me a lot of freedom to experiment and extrapolate." Slowly this work has earned her enormous recognition. The designer has already had her work exhibited at privileged institutions such as New York's Metropolitan Musuem of Art, the Musée de la Mode et du Costume of Paris, and the Victoria and Albert Museum in London. Happily, this month the Fashion Institute of Technology in Manhattan is celebrating her gift for functional modernism in a one-women show. You can see her futuristic look at "Yeohlee: Supermodern Style," on view at FIT (Seventh Avenue at 27th Street) Oct. 23-Jan 5. -- BY RUTH PELTASON