Onion is the cafe that set the template for Seongsu. Opened in a stripped-back old factory and metalworks, it left the raw concrete, exposed rebar, and industrial fittings exactly as found, then filled the space with light and a counter heaped with pastries — the pandoro dusted in a small mountain of powdered sugar became an Instagram fixture.
The look has since been copied across the district and the country, but the original still draws a queue, especially at weekends. Go early for a quieter morning, grab the pain au chocolat or a savoury bread, and take in the post-industrial cathedral of a room that turned a worn-out shoe-factory quarter into Seoul's most fashionable neighbourhood.