Recent theoretical work has suggested that urban food security is the result of food system interactions. This work highlights the challenge of assessing household-level food insecurity and relating it to the broader food system. One priority is to develop food security metrics that incorporate household inter-actions with the food system retail environment. The Hungry Cities Food Purchases Matrix (HCFPM) is one such metric that has been developed for situating household food sourcing behaviour within the urban food system. The matrix has been successfully administered in a number of cities in the Global South by the Hungry Cities Partnership. This paper discusses the administration of the HCFPM in a 2014 household survey of Maputo in Mozambique and illustrates how it can provide unique insights into the interactions between households and the broader food system. The HCFPM therefore paves the way for a new frontier in urban food system research in cities of the Global South.