The owner is a friend of a friend. He and his wife came from Taiwan so I assume this should be the most authentic Taiwanese food in Beijing. Their Lu Rou Fan is super and it's NOTHING like bellagio/yipin sanxiao/any cheap roadside gaifan. I love the pickle that comes with Lu Rou Fan. Also try their ji tui fan (chicken rice), meatballs, tempura (tien pu la) and yan su ji (salty fried chicken). Tips: ask for their chili sauce to boost your appetite :D
They also have a collection of Taiwanese soft drinks like Hey Song sarsaparilla, Guava juice and Taiwan beer. If it's not hidden inside a hutong, I believe this restaurant could be so popular among the NLGX fans.