Building on the long-standing tradition of challenging oppression and questioning whose interests are being served in the field of language education, we report on a study that involved a group of U.S.-based graduate students who collaborated with a ninth-grade English teacher in Nepal. The study comes out of a larger project that sought to internationalize the curriculum of a graduate educational linguistics course at a U.S. university. At the heart of this internationalizing curriculum endeavour was a commitment to expose graduate students in the U.S. to the issues of language teaching outside of the U.S. This was done through co-designing of a unit of lessons, with six graduate students meeting virtually with their teacher partner, Ditya, in Nepal over the course of a semester. The graduate students and Ditya constitute our research participants. The graduate student participants learned about the need to develop pedagogical materials that were relevant to the local context in Nepali classroom, and not attempt to transplant a Western-centric curriculum onto the Nepali classroom. In keeping with recent calls to decolonize higher education, we illustrate how critical theory in general and decolonizing pedagogy in particular can be infused into a U.S. graduate curriculum by drawing on the rich, indigenous knowledge and resources of a teacher collaborator from the Global South. We do this by reporting how this critical, decolonizing goal was realized through collaborative professionalism, which is characterized by the sharing of knowledge, skills, and experience to improve student achievement, reflection, dialogue and collective responsibility.