YOUNG local pianist Tammy Lum, whose career is now firmly established in the United States, will give her debut recital in the territory at the City Hall next month. Lum, the winner of the 1995 New Orleans International Piano Competition, won first prize in the 1987 William Boyd Competition and the 1988 Manhattan School of Music Concerto Competition. In 1990, she won the Leschetizky Foundation Competition and first prize in the Five Town Music and Arts Foundation Competition. Lum will play works of Bach, Strauss, Faure and Granados in the recital, which will be held at the City Hall Theatre on January 12 at 8 pm. Tickets at $90 and $60 are available at Urbtix outlets, with half-price concession for senior citizens, the disabled and full-time students. For reservations, call 2734 9009 and 2734 2000 for inquiries.