Katsuobushi, made from skipjack tuna (commonly known as bonito), is a cornerstone of authentic Japanese cuisine. This delicacy is rich in inosinate, a compound that imparts the savory umami flavor so beloved in Japanese dishes. When inosinate is combined with glutamate—another umami-rich amino acid found in ingredients like kombu (dried kelp)—it creates a powerful synergistic effect, elevating the umami experience to new heights. This is why dashi, the traditional Japanese soup stock, relies on both dried bonito flakes and kombu to achieve its distinct and rich flavor.

The production of katsuobushi is an art form in itself. The bonito is first filleted and simmered before undergoing several rounds of smoking. Following this, the fish is fermented and sun-dried over several months, resulting in a product so hard that it's often referred to as one of the toughest food items in the world.

To harness the umami of katsuobushi in cooking, these hardened blocks are shaved into paper-thin flakes. This process maximizes the surface area, allowing the umami flavors to quickly infuse into boiling water. Japanese chefs skillfully remove the flakes at the right moment to ensure a pure and clear stock, preserving the delicate balance of umami.