Every October a few emails come in with a photo of a chipped Japanese knife and a butternut squash sitting in the background looking innocent. The squash always wins. Here's why, and how to get through winter squash and pumpkin without feeding a $200 gyuto to one.

Why squash chips Japanese knives

It isn't the hardness of the squash, oddly. A thin Japanese blade will push through a butternut rind just fine. The damage happens after the blade's in.

Squash is dense and the cut faces grab the blade. When the knife's buried halfway through a kabocha, every instinct says twist it, lever it, rock it to finish the cut. On a thick German chef's knife that works, because the edge is ground at 20 degrees a side and the steel's soft enough to flex. On a Japanese knife ground at 12 to 15 degrees in steel at 60 HRC or more, the edge doesn't flex. Sideways pressure snaps a bit out of it. The chip repair page exists mostly because of squash, frozen food, and bones, in roughly that order.

The other cause is the stem. People cut toward it, hit it, and push. A squash stem is basically a piece of wood. Cut it off first with something cheap, or go around it.

And there's a third, sneakier one: the blade wedging. A tall, dense squash grips the sides of the blade so hard that it stops moving, and then people do the thing where they lift the whole squash off the board with the knife stuck in it and bang it back down. That's a sideways shock to the edge every time it lands. I've done it. Don't.

The one rule, and the four habits

The rule is this: the blade goes straight down and straight through, and if it won't go through, you stop and do something else. You never, ever finish a cut by bending the knife sideways. Everything else I'm about to say is just ways of making that easier to stick to, because in the moment, with a squash half-cut and dinner late, the urge to lever is strong.

So. Start the cut with the heel rather than the tip. The heel's the thickest, strongest bit of the edge, and if you push forward and down from there the tip never has to go into hard rind at all. I'd keep it out entirely on a big kabocha.

Take a thin slice off the top and bottom before anything else, so the thing sits flat. A squash that rolls is how people end up in A&E, and a squash that wobbles is exactly what tempts you into twisting.

Score first. Drag the edge along where you want to cut to leave a shallow groove, then set the heel in it and push. The blade follows the groove instead of skidding off the rind, which is the other way people get hurt.

And if it's a real brute, soften it. Three or four minutes in the microwave on a plate, or ten in a hot oven, takes the fight out of a kabocha or an acorn squash without cooking it enough to matter. This is what most Japanese home cooks do with kabocha, by the way, which in my experience is the hardest squash you'll ever meet. Nobody over there is wrestling one raw.

Which knife

Not the thinnest one you own, whatever the instinct says. A laser-thin 63 HRC gyuto is the wrong tool here for the same reason it's wrong for chicken bones. What you want is whichever knife in the drawer has the most steel behind the edge, even if it's not the one you love.

A heavier Western-style gyuto in a tougher steel is ideal. Our Classic 8" in AUS-8, 58 to 60 HRC with a bit of meat behind the edge, will go through a season of squash without a mark. The Classic vs Premium page explains why the softer steel is sometimes the smarter choice.

A Chinese-style slicing cleaver works well too, as long as it's the thin slicing kind and not a bone cleaver. All that blade height means you've got leverage without needing to twist, and the weight does most of the pushing for you.

If every knife you own is a thin Japanese one, do yourself a favour and buy a $25 stamped Western chef's knife to live in a drawer for squash, frozen things, and bones. I've got one. Everyone I know who's serious about their knives has one. It's the cheapest insurance you'll ever take out on the good ones.

And which knife not to use

Anything in SG2, R2, ZDP-189, or HAP40 at 63 HRC and up. Anything with a laser grind, Takamura being the obvious one. Any thin carbon-steel Sakai gyuto. Any single-bevel knife at all; the geometry steers and a squash will send a yanagiba sideways in a heartbeat. A santoku's usually fine on the softer squashes but short on a big butternut, so you end up with the tip buried, which is where tips break. And not the petty, obviously, though people try.

If you're not sure where your knife falls, the HRC page gives a rough hardness for most common steels. Below 60 and with some thickness behind the edge, go ahead. Above 62 and thin, pick a different knife.

Board and setup

Small thing that matters more than it should: cut squash on your biggest, most stable board, with a damp towel under it so it can't skate. A board that slides under the force of a push cut is another source of the sideways load that chips edges. Stand square to the board, both feet planted, and push with your body weight through a straight arm rather than muscling it with your wrist. If you find yourself up on your toes leaning over a kabocha, the squash is winning and it's time for the microwave.

Keep the board clear while you work, too. Half a squash rolling into the blade mid-cut is how I got the one real cut I've had in a kitchen, and it wasn't the knife's fault.

Butternut, the way I do it

Butternut is the easy one, honestly, because it's two different vegetables pretending to be one. The neck is solid all the way through and the bulb is where the seeds live. So I take the stem end and the base off, stand it up, and cut it in half right where the neck meets the bulb. The neck then lies flat on its cut face and gets sliced into rounds or planks with plain push cuts, no drama. The bulb I split lengthwise, scoop with a spoon, and cut into wedges or cubes depending on what dinner is.

Peel before or after, I genuinely don't think it matters. A Y-peeler takes butternut skin off without much effort, and I'd rather do that than put a thin knife anywhere near the job.

Kabocha

Kabocha I treat with more respect. Whole, into the microwave for three or four minutes first, no exceptions. Then the stem comes off with the cheap knife. Stem side down on the board, heel of the good knife sitting on top, and I push straight down with my free hand flat on the spine. It splits, usually with a satisfying crack. Seeds out, each half cut-side down, and wedges with the heel. The skin's edible on a kabocha so there's no peeling, which is one of the things I like about it.

Japanese cooks have a trick for the stubborn ones worth passing on. After the microwave, if it still won't split, they put the tip of a sturdy knife into the stem hollow and push down on the spine with the heel of the hand, letting the knife act as a wedge from the centre out rather than slicing from the edge in. The rind cracks along its natural ribs. It works, but only with a thick, tough knife. Not with the good one.

Acorn, delicata, spaghetti, and the rest

Acorn is the hardest after kabocha, with deep ribs that make scoring useless. Microwave it, cut it through the stem end straight down the ribs, not across them, and expect to use some force. Delicata is soft enough that any knife handles it and the skin's edible; I use the good gyuto on delicata without a second thought. Spaghetti squash has a thin but surprisingly tough rind and a lot of air inside, so the blade goes in easily and then stalls; score it all the way round first, microwave it five minutes, and it'll usually split with a push. Hubbard and the giant blue ones are a job for a cleaver or a hatchet and I'm not joking; the traditional method is to drop them on a concrete floor.

Pumpkin

Carving pumpkins are soft enough that any knife will do, though a serrated one or one of those little pumpkin saws leaves cleaner lines if you care about the face. The ones you actually eat, sugar pumpkins and pie pumpkins, I treat like a small kabocha. Stem off, split from the top down with the heel, scoop, wedge.

Frozen squash, since it comes up

Bags of frozen cubed butternut are a decent shortcut and nobody should feel bad about them. But never, ever put a Japanese knife into a frozen block of anything, squash included. Frozen vegetable matter is harder than the rind ever was, and the ice crystals act like grit against the edge. If the bag's frozen into a lump, bang it on the counter to break it up or let it thaw for ten minutes. If you must cut frozen squash, it's a job for the $25 beater, and even then I'd think twice.

Once it's cut

This is where the Japanese knife comes back out. Peeled, seeded squash is just a dense vegetable and a thin gyuto goes through it beautifully. Cubes for roasting, thin slices for a gratin, batons for a stir fry; the hard part's over and the good knife does the nice part. The only thing to watch is still the twist. Squash flesh is dense enough to grip even a thin blade on a deep cut, so keep the strokes straight and let the knife's own sharpness do the work.

If you chipped it anyway

Under 1mm sharpens out on a 1000 stone in a few minutes. Bigger than that wants a coarse stone, 220 to 400, and some patience. The repair guide walks through it. The knife will be fine. So will the squash, which will be in the oven by the time you've finished sharpening.

And look, it happens to everyone. The first Japanese knife I ever chipped went into a butternut in about 2011 and I still remember the noise. Learn the no-twist rule from that one squash and you'll probably never do it again.

Andrew Kuzmin · Editor-in-Chief, Okami Blades