This laboratory experiment leverages the pedagogical value and multidisciplinary nature of biodiesel production from vegetable oil to introduce students to continuous-flow chemistry, a modern and rapidly growing approach to chemical synthesis. An interdisciplinary approach exposes students to the practical and conceptual aspects of modern continuous-flow chemistry while simultaneously reinforcing core organic chemistry techniques and investing students in issues of sustainability. Students screen reaction conditions in flow through an inquiry-guided approach and make evidence-based decisions to accomplish the sustainable conversion of waste cooking oil into biofuel. The laboratory experiment is designed to be highly modular and can be completed in two, three, five, or eight laboratory periods. By incorporating the burgeoning field of continuous-flow chemistry into the educational infrastructure, the experiments allow students to develop skills that are highly valued in the modern chemical workforce.