Great Middle Way is a translation of Maha Madhyamaka, which is what our Lamas call the Jonang view of the Dharma.
The Great Middle Way is found beyond (not between) all extremes: beyond austerity and hedonism, eternalism and nihilism, sectarianism and eclecticism, dualism and monism.
“It is not this. It is not that. It is not both. It is not neither.” —Nagarjuna