The twisted Gan--Gross--Prasad conjecture considers the restriction of representations of GL_n to a unitary group. In this talk, I will explain the relative trace formula approach to the global twisted GGP conjecture. In particular, I will discuss how the fundamental lemma that arises can be reduced to the Jacquet--Rallis fundamental lemma, which allows us to prove the global twisted GGP conjecture under some unramifiedness assumptions and local conditions.