Since agriculture is a large source of emissions today, changes in our food production and consumption are required to reach EU climate goals. This study aims to find out if nudging combined with knowledge-based system can be used to influence customers’ choice towards more sustainable food. To investigate how the knowledge-based system should be created a quasi-field experiment was performed to measure the effect of re-ordering a menu (with vegetarian options on top). Previous studies have shown that nudging yields result, but without reporting how customers feel about being nudged. To investigate this, a selection of participants with different demographics (age, sex etc.) were presented digital lunch menus and their feelings and thoughts were observed through qualitative research in the shape of think aloud sessions. The participants were presented with three menus that used different nudging tactics. The results were used to create a conceptual model of a digital menu system based which builds upon knowledge-based systems. The system integrated social, label and order nudges as well as profit margin to create a system that is sustainable in the perspective of climate, as well as economy.