In the present article it is proposed that a focus on taste is instrumental for promoting a green transition towards a more sustainable eating behaviour involving a more plant-based diet. In particular, it is pointed out that umami is a key driver for this transition because on the one side green food like vegetables typically lack this basic taste that humans on the other side are genetically primed to crave by evolution. We highlight how a mechanism of synergy operates and can be applied to enhance umami taste by a combination of free amino acids and free nucleotides in the same food item either by culinary preparation or by appropriate food pairing. Examples of the power of umami synergy are given, with some focus on sustainable marine foods like bivalves and cephalopods as well as vegetables. Finally, we demonstrate how umami taste as a driver for sustainable eating can be brought to work in the context of communication to children as well as the general public, e.g., by gamification.