Ven. Hahn was brought up in the Rinzai Zen tradition. However, he combines various other schools, such as Theravada, and Pure Land, into his teachings. This was actually quite common in Vietnam, which took a kind of similar approach to Buddhism that the Chinese did, which was to not really separate all the various teachings into various schools, as if they were not all important to the Buddhist path.
"If you want to travel the Way of Buddhas and Zen masters, then expect nothing, seek nothing, and grasp nothing." -Dogen