SANTOKU
SANTOKU
Updated August 2026 · 8 min read · UK Japanese knife specialists
In short
Halve the potato lengthways, lay each half flat and halve it again to make four quarters, then cut each quarter into two or three wedges depending on how big the potato is. Keep every cut running through the centre line of the potato so each wedge ends up a similar thickness and the whole tray cooks at the same rate. A medium potato gives you eight wedges; a large one gives ten to twelve.
Wedges are the easiest potato shape to get wrong. Cut them by eye and you end up with a tray where the thin ones are burnt, the fat ones are still raw in the middle, and nothing is ready at the same time. The fix is not a gadget — it is a repeatable sequence of cuts and a blade that goes through a dense raw potato without wandering.
This guide covers the cutting method step by step, how many wedges to expect from each potato size, which potatoes work best in the UK, and how to cut them safely.
Contents
The step-by-step cutting method
The whole technique is halve, halve again, then split each quarter. Every cut runs lengthways down the potato and passes through the centre, which is what keeps the wedges even.
1. Scrub and dry the potatoes
Wash the potatoes under cold running water and scrub off any soil, then dry them properly with a tea towel. A wet potato skids on the board, and a skidding potato is how people cut themselves. Drying also matters later: surface water stops the wedges crisping in the oven.
2. Decide on skin-on or peeled
Leave the skin on for wedges. It holds the wedge together while it cooks and gives you the crisp edge that makes a wedge a wedge rather than a chip. Only peel if the skins are damaged, green or thick and papery.
3. Create a flat base
Set the potato on the board and cut it in half lengthways, following the long axis from one end to the other. You now have two halves with a flat cut face. Turn both of them cut-side down. This is the single most important safety step on the whole job — a round potato rolls under the blade, a flat-sided one does not.
4. Quarter each half
Take one half, cut-side down, and cut it in half again lengthways through the centre line. Repeat with the other half. You now have four quarters, each a long triangular prism. For small potatoes you can stop here.
5. Split each quarter into wedges
Stand each quarter on one of its flat sides and cut it lengthways again — into two wedges for a medium potato, or into three for a large one. Aim the blade at the centre of the rounded skin edge so that the wedge you cut off has roughly the same amount of flesh as the one left behind.
6. Check thickness, not shape
Run your eye along the batch and compare the thickest part of each wedge. Even cooking depends on thickness, not on the wedges being identical triangles. Trim anything obviously fatter than the rest — around 2–3 cm across the thickest point is a good target for roasting.
How many wedges per potato (at a glance)
Use this as a guide rather than a rule — potatoes vary, and so do ovens. Times below assume a preheated oven at roughly 200°C fan (220°C conventional, gas mark 7) on a single layer with a little oil, turned once halfway.
| Potato size | How to cut | Wedges | Rough roasting time |
|---|---|---|---|
| Small (about 150 g) | Halve, then quarter — stop there | 4 | 25–35 minutes |
| Medium (about 200–250 g) | Halve, quarter, then split each quarter in two | 8 | 30–40 minutes |
| Large (300 g or more) | Halve, quarter, then split each quarter into two or three | 10–12 | 35–45 minutes |
Whatever the size, judge by colour and feel rather than the clock: the wedges are done when the edges are deep golden and a knife tip slides into the thickest part with no resistance.
Choosing the right potatoes
Wedges want a floury or all-rounder potato — enough starch for a fluffy middle, enough structure to hold the wedge shape. In UK supermarkets that means:
- Maris Piper — the default British roasting and chipping potato. Floury, crisps well, holds its shape as a wedge.
- King Edward — floury and fluffy inside, very good for oven wedges. The tubers are often irregular, so expect to trim a few odd ones.
- Rooster — a red-skinned all-rounder that roasts well and looks good with the skin left on.
- Desiree — firmer and waxier than Maris Piper, so the wedges hold together neatly, with a slightly less fluffy centre.
- Charlotte and other salad potatoes — waxy and low in starch. They will not go fluffy inside, but they hold their shape well and are worth using if that is what you have.
Whatever you buy, pick potatoes that are firm all over with no soft patches, green tinges or sprouts, and try to choose ones of a similar size so that a single batch cooks evenly.
Which knife to use for potato wedges
A raw potato is one of the densest things you cut in a domestic kitchen — no give at all, and a hard skin the blade has to break through before it can travel. That combination is exactly where a blunt or flexible blade slides sideways off the skin instead of biting into it. This is a safety point rather than a sales line: most potato-cutting injuries are a blade skating off a curved surface, not a blade being too sharp.
What you want is a wide, rigid, genuinely sharp blade long enough to pass through a large potato in one movement. A santoku or a gyuto chef knife both do this well. Our Japanese-steel knives are made with hardened VG10 and AUS-10 steel cores, which take and hold a fine edge — that keeps the blade cutting rather than wedging as it goes through dense flesh.
Haruta 7 Inch VG10 Japanese Damascus Steel Santoku Knife — £89.99
★★★★★ 4.88 (112 reviews)
A 7 inch santoku is the natural wedge knife. The blade is tall enough to keep your knuckles clear of the board and short enough to stay controlled through a hard skin, and the flat profile means the whole edge lands at once instead of rocking off the curve.
Pros
- Tall, rigid blade for safe knuckle clearance
- Flat edge bites straight into potato skin
- VG10 core holds a fine edge
Cons
- Short for very large baking potatoes
- Wooden handle needs hand washing and drying
Haruta 8 Inch VG10 Japanese Damascus Steel Gyuto Chef Knife — £89.99
★★★★★ 4.88 (112 reviews)
If you cook big baking potatoes, the extra inch matters. An 8 inch gyuto clears the widest potato in a single stroke, so you are not sawing at a half-cut wedge — and it is the more versatile blade if you only want to own one knife.
Pros
- Long enough for the biggest baking potatoes
- One clean stroke instead of sawing
- Most versatile shape for everyday prep
Cons
- Feels large on a small chopping board
- Wooden handle needs hand washing and drying
Aiko Black Damascus Steel Knife with Coloured Black Resin Handle — from £64.99
★★★★★ 4.94 (120 reviews)
The cheapest way into a properly rigid blade. The resin handle is sealed and dishwasher-tolerant, which suits a knife that spends its life on root vegetables, and the range includes several blade shapes so you can pick the size that suits your potatoes.
Pros
- Lowest entry price of the three
- Sealed resin handle shrugs off water
- Choice of blade shapes and sizes
Cons
- Price varies by blade size chosen
- Less blade height than the santoku
Not sure which blade you need?
Our chef knife collection covers the sizes and shapes that handle dense vegetables like potatoes, squash and swede — all made with Japanese steel and shipped from the UK.
Cooking your wedges
Cutting is most of the job, but a few habits make the difference between wedges and disappointment.
- Dry them properly. After cutting — and especially after soaking — pat the wedges dry. Surface water steams the outside instead of crisping it.
- Give them room. Spread the wedges in a single layer with a gap between each one. Crowded wedges steam each other.
- Oil lightly, season after. A thin coating of oil is enough. Salt draws moisture out, so many cooks prefer to season part way through or at the end.
- Skin side down first. Sitting the wedges on a cut face gives you a flat, browned surface, then turn them once so the second cut face colours too.
Treat all times and temperatures here as a starting point. Ovens vary a lot, and the doneness test — deep golden edges, no resistance to a knife tip — is more reliable than any number.
Frequently asked questions
How many wedges do you get from one potato?
A medium potato of around 200 to 250 g gives eight wedges: halve it lengthways, halve each half to make four quarters, then split each quarter in two. A large potato of 300 g or more gives ten to twelve, and a small one is best left at four quarters.
Should you peel potatoes for wedges?
No. The skin holds the wedge together as it cooks and gives you the crisp edge that makes a wedge different from a chip. Scrub the potatoes well instead, and only peel if the skins are damaged, green or unusually thick.
Do you soak potato wedges before cooking?
Soaking is optional. Half an hour in cold water rinses surface starch off the cut faces, which helps them crisp and stops them sticking together, and it also keeps cut potatoes from browning if you prepare them ahead. If you do soak them, drain and dry them thoroughly before they go anywhere near oil.
What knife is best for cutting potato wedges?
A wide, rigid, sharp blade long enough to cross the potato in one stroke — a santoku or a gyuto chef knife. Avoid small paring knives, which are too short to control through a dense potato, and avoid a blunt blade, which skids off the skin rather than biting into it.
Which potatoes are best for wedges?
Floury and all-rounder varieties. In the UK that means Maris Piper, King Edward, Rooster or Desiree. Waxy salad potatoes such as Charlotte hold their shape neatly but will not give you a fluffy centre.
How do you stop the knife slipping when cutting a potato?
Dry the potato, put a damp cloth under the board so the board cannot move, and make your first cut the one that creates a flat face. Once the potato is sitting cut-side down it cannot roll, and every cut after that is made against a stable surface.
