There is growing pressure from the public health sector, government, environmental, medical and scientific fields to teach young people about food. However, little is known about pre-service teachers' preparation in this area. This article addresses this gap by providing a case study of one approach to food education, which was purposefully designed to bring together two fields--health education and education for sustainability (EfS)--in teacher education in Victoria, Australia. This article outlines the ways in which this approach has the potential to challenge the conventions of both fields and "spaces" of health (first space) and sustainability (second space), and gave rise to a possible "third space" (Soja, 1996). This article uses data collected from Promoting Health Education, a 10-week course designed for generalist primary school pre-service teachers. It also utilises reflections from pre-service teachers and teacher educators (also the authors) to explore how they navigated first, second and third spaces. In doing so, the authors examine some of the learning potentials and difficulties within third spaces, including: designing third spaces; wrestling with the dominance of first space; complexities of second space; and questioning what might be lost and gained through the design of third spaces.