The latest episode of Vendors: International explores the meticulous process of making bonito flakes at renowned shop Kaneshichi Shoten in Makurazaki, Japan. A key ingredient in Japanese cuisine, bonito flakes are made from smoked and fermented tuna and give dashi broth its signature umami flavor.
Katsuobushi, or bonito flakes, are a seasoning ingredient made by boiling, smoking, fermenting, and drying tuna. This method has existed in Japan for centuries, and has been passed down for generations at the 60-year-old Kaneshichi Shoten, which provides the ingredients to restaurants like Adi in Tokyo and the Nobu pop-up in Kyoto.
“These traditional techniques that we’ve inherited from the past, perhaps it’s too much to say I want to preserve them, but that’s how I feel,” says Yusuke Sezaki, a craftsman at Kaneshichi Shoten. “Makurazaki produces half of all the katsuobushi made in Japan.”
The process starts at a bonito auction where 30 different companies bid on the best fish. Next, the fish is simmered at high temperatures to stop the decay of inosinic acid, lifting and strengthening the umami flavor. After the bonito is cut and steamed, craftspeople remove the bones by hand to prevent the shape from warping and they add fish paste to fill the gaps where the bones were removed.
“In today’s Japan, it might seem like meaningless work,” Sezaki says. “But in the past, this little task was proof that it was done by an amazing craftsman.”
Once this is done, the fish is brought to a three-story smoke room where, over 24 days, rising smoke removes moisture from the fish and imbues a unique flavor profile. Next, the fish is left out in the sun to dry for a week, developing a green mold that Sezaki says is “best to be powdery, not sticky.” Next up is the fermentation room, where oil from the fish is broken down and the umami flavor continues to heighten.
“Being able to grow in a relaxed and comfortable state might have an impact on the quality of katsuobushi,” Sezaki says. “This is where the bonito grow to their fullest.”
These bonito flakes end up in dishes like green curry with golden eye snapper from chef Kanchan Adhikari of Adi. Adhikari steeps the bonito flakes to make a dashi broth and adds that to spinach, dill, cilantro and combines that with traditional Nepalese spices like white coriander and cumin.
“You have to really understand your ingredients and the best way is to build a close relationship with your suppliers,” Adhikari says. “It took two or three full months to make, right? Seeing how hard everyone worked made me want to be more thoughtful about how I use katsuobushi.”
Watch the newest episode of Vendors: International to watch how bonito flakes go from the fish auction to high-end dishes.
