The food-energy-water (FEW) nexus framework calls for a systems perspective on addressing complex sustainability challenges. As a sustainability science field, nexus research should in theory bring together transdisciplinary approaches drawing from a range of stakeholder knowledge and experiences. This approach would align with the competence-based training for future sustainability leaders advocated for in sustainability education literature. In practice, the field is dominated by techno-scientific approaches with superficial or peripheral attention paid to issues of social justice and community engagement. In this article, we explore how this imbalance in the literature reflects a breakdown between the ideals of sustainability training and the reality of training at the nexus and describe obstacles that may be contributing to this breakdown, including a prejudice towards the idea of "objective" science, institutional incentives, and disciplinary culture. To address these concerns, we introduce a research project focused on assessing the training of future researchers at the FEW nexus and exploring how these programs train students in particular views of what is important at the FEW nexus, such as technological solutions, stakeholder collaboration, and/or issues of equity and justice. It will also provide recommendations for creating open learning environments that are competence-based, and that incorporate multiple methods, acknowledgments of limitations, and alternate ways of knowing.