Ryba po kaszubsku is a traditional Polish dish originating from the Kashubia region. It typically consists of fish, often herring, marinated in a mixture of vinegar, onions, and spices. The dish is usually served cold and is popular during festive occasions and family gatherings. The preparation involves layering the fish with sliced onions and pouring the marinade over it, allowing the flavors to meld. Ryba po kaszubsku is often accompanied by bread or potatoes, making it a hearty and flavorful meal that showcases the culinary heritage of the Kashubian people.