Fermented sushi, also known as narezushi, is a traditional form of sushi that involves fermenting fish with rice. This process can take several months, allowing the fish to develop a unique flavor and texture. The rice is often discarded after fermentation, as its primary purpose is to preserve the fish. This ancient method of sushi-making originated in Southeast Asia and spread to Japan, where it evolved into various styles. Fermented sushi is less common today but is appreciated for its rich taste and historical significance in the culinary world.