This report analyses the economic, social and environmental sustainability of the food system in the areas around Iringa and Dodoma, in southern and central Tanzania, and studies the potential role of diversification and indigenous vegetables to advance its sustainability. It is the third output of the Sustainable Agrifood Systems Strategies (SASS) programme, a multidisciplinary consortium initiative that, between 2017 and 2020, conducted research and dialogue activities in Tanzania and Kenya. This document was written by a team of anthropologists, economists and political scientists from different universities and knowledge centres in the Netherlands, Italy and Tanzania. The first chapter introduces the SASS approach to sustainable food systems. A ‘food systems approach’ is a way of thinking and acting that considers the whole food system. This includes the biophysical characteristics, activities and actors that characterise the food system, the way these interact and the outcomes of those interactions. We argue that using a food systems approach can help practitioners and policymakers better understand the complex and interrelated drivers of food system sustainability and identify trade-offs between different policy objectives. By providing a ‘big picture’ view, a food systems approach can thus inform more coherent, effective, and context-appropriate policies and interventions to support sustainability transitions. Recognising that food system transformation is inherently political, our approach combines an analysis of the food system under study and its unique sustainability challenges with an analysis of the system’s political economy dynamics that investigates the power, interests and incentives different actors face in shifting or maintaining the status quo. This approach allows us to develop politically feasible ‘transformation pathways’, i.e., coherent mixes of policies and actions for improved food system sustainability.