Katsuo-bushi or dried bonito is an indispensable ingredient in Japanese cooking. Today it is found in bags of pinkish brown flakes Kezuri-bushi (kezuri means to shave or shaven) in Japanese supermarkets. Traditionally, a large chunk of dried katsuo is shaved as needed using a wooden Katsuo-bushi shaver. Katsuo-bushi is used in dashi (the stock that is the basis for so many Japanese dishes) or as a garnish for tofu or ohitashi (boiled spinach). Its flavor is full of umami, the flavor that gives the dish a savory and satisfying taste.
Katsuo-bushi was created as means of preserving fish. The first step in curing the katsuo is to fillet the fish (a large fish yields about 4 fillets). The pieces are then arranged in sieves and lowered into water that is kept at about 90°C. After simmering for 2 hours or so, the fish is removed from the water. Any remaining bones are removed and the pieces are trimmed to form blocks. Next, the blocks are smoked for several hours and then cooled to room temperature. They are then smoked and cooled again for 2 weeks to 3 weeks.
After shaving off the natural tars from the surface and reshaping the blocks of smoked fish, it is time to cure the blocks. The blocks are placed in a room with tightly controlled temperature and humidity until a mold develops on the surface. They are then dried in the sun. The mold breaks down the fat in the fish and builds up the amino acid content which gives the katsuo-bushi its umami flavor. This fermentation will repeated about 4 to 5 times, the entire process taking about 4 to 6 months.
I had never thought of making my own Kezuri-bushi until I encountered a Katsuo-bushi shaver and some locally made Katsuo-bushi at Sunday market in Kochi. Since I don't have access to real katsuo-bushi in NYC, I thought, why not buy one and make authentic Kezuri-bushi? 
I looked around the market and saw the traditional wooden shavers. One vendor showed me a more economical and an easy-to-use plastic shaver. The plastic shaver box was a little smaller in size, but it was easy to clean and you can put the shaver box in a refrigerator to keep the freshly shaved Kezuri-bushi. I liked the idea of it being easy to clean, so I decided to go for the plastic one instead of an authentic looking wooden shaver.
I opened the package with the block of Katsuo-bushi. The aroma was very strong and hit the nose immediately. It has the smell of a concentrated version of shaved Katsuo-bushi, almost similar to katsuo rice sprinkle smell. The Katsuo-bushi felt hard as a rock, and I had to press hard to shave it. I moved my hand back and forth couple times and saw the result of my shaving. I opened the box and saw thick ribbon-like Kezuri. The aroma was very strong, and I was surprised how aromatic the Kezuri-bushi was. I sprinkled the Kezuri on a prepared onion salad.Onion Salad
1 Vidalia Onion
Sesame dressing (preferably)
Kezuri-bushi
1. Slice the onion using mandolin or benriner
2. Soak the onion into the ice cold water for 15 minutes.
3. Drain the onion, and place them in a bowl. Pour the sesame dressing or any other your favorite dressing and mix them.
4. Place the onion salad on a plate. And, sprinkle with Kezuri-bushi.
