How a Master Sushi Chef Butchers a 250 Pound Bluefin Tuna — Omakase

At the pinnacle of Japanese culinary craft sits the art of edomae sushi, where the mastery of fish butchery is as critical as the final bite. In this masterclass from Eater’s Omakase series, Chef Ingi Son of San Francisco’s Michelin-starred restaurant, The Shota, demonstrates the methodical breakdown of a massive 250-pound bluefin tuna. For professional chefs, the demonstration is a study in anatomical precision, knife control, and waste minimisation when handling one of the ocean's most expensive ingredients.

Anatomy and Knife Progression

Deconstructing a fish of this scale requires a deep understanding of its skeletal structure and muscular divisions. Chef Son begins by systematically removing the head and collar (kama), a process that demands clean cuts around the collarbone to preserve as much premium meat as possible.

The progression of knives is vital. The chef utilises specialised blades, transitioning from heavy-duty knives for bone-adjacent cuts to long, slender slicing knives like the yanagiba for partitioning the loin. The primary objective is to separate the fish into four main quarters (two back loins and two belly loins) through a refined variation of the san-mai oroshi (three-piece filleting) technique. Precision is paramount: a single misplaced stroke can tear the delicate flesh, bruising the highly prized o-toro (fatty belly) or akami (lean loin) and reducing its commercial value. Chefs must maintain an incredibly sharp edge on their blades to glide through the connective tissue without applying downward pressure.

Yield Optimisation and Omakase Curation

With bluefin tuna costing thousands of pounds per specimen, yield preservation is a chef's ultimate priority. Chef Son demonstrates how to harvest the scrapings from the backbone, known as nakaochi, using a spoon or specialised tool. This highly flavourful meat is immediately earmarked for tartares, gunkan maki, or handrolls, ensuring zero wastage.

The bone, skin, and head are also processed to extract maximum culinary value. Once partitioned, the loins are aged under strict temperature controls to allow the natural umami to develop. The transition from the lean, iron-rich akami to the rich, buttery o-toro requires distinct preparation methods, including precise scoring to tenderise the fat-rich membranes. Chef Son's innovative omakase approach highlights how temperature control, careful curing, and knife angles lift these distinct cuts into a seamless, luxurious dining experience.