Sushi & knives

I have been making sushi since 2003 and i do not call myself a chef. I am a craftsman who works in fish. My culinary school was watching: standing next to cooks at work, figuring out where a shortcut costs you the result, and staying humble in front of a problem that never fully solves, which is forming consistent shapes and flavours out of material that is different every day.

The Japanese word for working like that is shokunin. It sounds grander than it is. It means look closely, don’t ask stupid questions, do it again until it is right. Which, now that i write it down, is also how i do everything else on this site.

moSushi, and why there is no kitchen chaos

In 2006 i founded moSushi, a mobile sushi bar, on a 20k budget and a state founder’s grant. Twenty years later it is still the main job: live sushi on Europe’s big trade fairs, K, drupa, Medica, Ambiente, Electronica, plus corporate events, private parties, and classes in our own training bar near Düsseldorf since 2007. Japanese companies book us repeatedly, which i take as the compliment it is.
mosushi.de

The bit i find genuinely interesting is structural. A restaurant cooks in the hope that guests arrive, so waste is built into the model, and the staff exist to absorb the uncertainty. That is where the rigid hierarchy comes from, the brigade system is literally borrowed from the army. We only ever cook what is already booked. Nothing waits for anyone, there is no variance to absorb, and therefore no need for a command structure to absorb it. I did not plan that as a philosophy, it just turned out that if you fix the demand side, a lot of the misery further down disappears on its own.

Honouring the material

If i have a specialty, it is this. Everything the craft is handed, the fish above all, was a living thing. So you get the maximum out of it and present it as preciously as you can. Waste is not a cost problem, it is a manners problem.

That is also where the sharpness obsession comes from, and it is not aesthetic. A dull edge tears cells. A properly finished one parts them, and the slice never knows it happened.

Knives, and what is actually going on at the edge

I sharpen on waterstones the traditional way, from a collection grown over years, Japanese naturals from the historic quarries near Kyoto among them. Self-taught, which mostly means i got everything wrong first and only later found out why.

At some point i put a microscope on the bench, because one material had stopped answering the usual signs. You normally read an edge by feel and by how it catches paper, and when that stops telling you anything you have to actually look. 1500x, now 2500x. A few things i only understood once i could see them:

Bite and sharpness are not the same thing. An edge “bites” because the grit leaves a sawtooth along the apex, and that sawtooth grabs. Coarser stone, bigger teeth, more grab. But sharpness in the other sense is apex radius, how few nanometres wide the very tip is, and that is what lets a polished edge wedge through on a push cut without any teeth at all. Two separate things that people constantly merge into one.

So motion and finish are independent. Push cuts want a small apex radius: dense vegetables, precise dicing, a square clean face. Draw cuts want length and low downward force: soft things that would squash, long slices, slippery skin. A yanagiba is a polished edge doing a draw cut, deliberately, because on fish you want the draw’s low force without the tearing that teeth cause. Toothy edges bite hardest and tear. Polished edges bite least and part. For raw fish you want the second one, always.

A knife does not get sharper on its own. There is a nice story that a knife becomes sharper and more “yours” the longer you use and sharpen it. The real mechanism is better than the story: every sharpening also removes steel further up the blade, so over years the whole cross-section thins, and a thinner blade wedges with less force. That is the “cuts like nothing else” feeling, and it is geometry, not magic. Left alone it goes the other way, freehand habit tends to raise the angle on a double bevel and fatten a single bevel. As for the knife becoming suited to you, mostly you are becoming suited to the knife. That part happens in your hands, not in the steel.

You can watch a blade straighten out over a career. Sharpening at a fixed diagonal removes material evenly enough that curves flatten. Look at knives that have had a daily medium-stone pass for twenty years and the belly has gone; a yanagi slowly drifts towards takobiki geometry. Nobody decided that, the stone did.

Ceramic

From 2012 to 2018 i presented ceramic knives for Kyocera at fairs and in eight live QVC broadcasts, sharpening on camera. Working that material properly is what put the microscope on my bench in the first place, and i am still grateful for the detour, because ceramic taught me more about edges than steel did.

Zirconia does not dull the way steel dulls. It is hard and it is brittle, so instead of rolling or rounding it chips, at a scale you need magnification to see. My own reading, from a lot of hours at the eyepiece: it chips itself into an equilibrium. The factory edge is ground far finer than the material can hold, so it breaks down quickly to a microscopic sawtooth, and then it sits there, essentially stable, for years. Which is why a ceramic knife feels spectacular for the first week and merely fine forever after, and also why it keeps slicing tomatoes long after you expect it to: that stabilised sawtooth is a draw-cutting edge. It is a real property, not a defect, it just is not the property the first week promises.

On knife myths, since there are many

Two i have chased down and can report on.

That it is somehow mandatory in Japan not to sell knives “too sharp” for consumers. There is no such rule. What is real is an industry habit of shipping a conservative edge, because a fine edge chips, buyers are not always careful, and manufacturers carry strict product liability. A widespread convention, reported by everyone as if it were law. Those two things are very easy to confuse, and i have fallen for the same kind of thing myself in my own field.

Which also explains the dropshipped knife ads with the invented Japanese forge, whose pitch is that a production error made the blades too sharp to sell legally, so here they are at 70% off. The whole scam runs on a regulation nobody has ever been shown.

One principle

Sushi is never finished, and every move has to be explainable. If i cannot say why i am doing something, i do not understand it yet, and then i am just copying someone.