How to Slice Potatoes in a Food Processor

The slicing disc is a flat disc with one raised blade. Food drops down the feed tube and is shaved off as the disc spins past the opening. Nothing else in the box does that job.

• The S-blade chops and purees. It gives chunks, and pulsing only makes smaller chunks.
• The shredding disc gives shreds, which is what you want for hash browns, not for a gratin.
• A dicing kit cubes, and a french-fry or ripple-cut disc makes those specific shapes.

The disc has to sit raised-blade side up and seat flat and dry on the stem. A disc that is upside down or riding on a wet stem will not slice cleanly, and on many machines the lid will not lock at all.

The disc most machines come with

Most full-size US processors ship with one fixed slicing disc of roughly 3/16 inch (4 to 5 mm). That is fine for roasting and a rustic gratin, and too thick for thin chips. Thinner discs, down to about 5/64 inch (2 mm), and adjustable discs are usually a separate purchase. An adjustable disc lets you dial thickness in millimeters; a fixed disc gives you one thickness per disc.

Match the slice to what you are cooking, because a gratin and a potato chip want very different cuts.

If your only disc is the stock 3/16 inch (4 to 5 mm) one, you are set for roasting and a rustic gratin. For chips you need a thinner disc, and there is no trick around that.

1. Set up the machine. Lock the bowl on the base, drop the stem in, seat the slicing disc flat with the blade side up, then lock the lid. The machine will not spin unless the bowl, disc and lid are seated in that order.
2. Wash the potatoes and peel if you like. Peeling is optional. Skin-on is fine for gratins, chips and roasts.
3. Cut to fit the feed tube. Halve or quarter each potato lengthwise so every piece has a flat cut face. A flat face down keeps the potato from tipping and gives even slices. Most machines need a medium potato halved; a wide feed tube can take a whole medium one.
4. Choose the chute. Use the large chute for whole or halved potatoes and the small chute for slender pieces and the last odd-shaped bits.
5. Pack the chute snug. A full chute holds food upright. A loose piece falls over and slices slanted, so set pieces side by side so they cannot wobble.
6. Position and process. Many manuals advise starting the disc so the blade sits just past the feed tube, so it reaches full speed before it meets food. Run on high, or the fastest setting the machine has; many have only on and pulse.
7. Press firmly and evenly on the pusher. Steady, not forced. Never push with fingers and never force food down the chute.
8. Work in batches. Do not overfill the chute or overload the motor, and empty the bowl between batches on big jobs.

Almost every bad batch traces back to how the food sat in the chute or how the disc was seated.

Browning is enzymatic. Cut surfaces react with oxygen and darken, and cold water shields them from air and slows the reaction. A splash of acid, about 1 tablespoon of lemon juice or vinegar per half gallon of water, lowers the pH and slows it further. Keep slices submerged in the fridge for no more than 24 hours; longer and they turn waterlogged and grainy.

Starch removal matters for crispness. For chips, fries and hash browns, rinse in cold water until it runs clear, several rinses, and soak hash brown potatoes about 10 minutes. Then dry them thoroughly in a salad spinner or a clean towel before frying, or the slices steam instead of crisping. For gratins and roasting you do not need to rinse, because the starch helps bind and brown.

The variety changes how the slice cooks, not how it comes out of the machine.

• Russets are high in starch and best for chips, fries and roasting. They crisp and fluff.
• Yukon Gold and other all-purpose potatoes are best for gratins and scalloped potatoes. They turn creamy and hold together.
• Waxy reds and similar hold their shape, which suits potato salad and boiling, and they crisp less when fried.
• Sweet potatoes are denser and harder. They slice fine, but use firm pressure, cut smaller pieces to fit, and expect the machine to work harder.

The slicing disc's edge is razor sharp. Handle it by the hub, never by the blade, always use the pusher and never your fingers, and unplug the machine before you remove the disc. Forcing food down the chute can damage the disc as well as your hand.

Clean the disc promptly. Potato starch dries hard and sticks to the blade and the hub, so warm soapy water and a brush right after use saves scrubbing later. Put it in the dishwasher only if the disc is rated for it.

A wide feed tube that takes a whole medium potato saves the most prep time, because you skip most of the cutting. Look for adjustable or swappable discs down to about 5/64 inch (2 mm) if you want chips; a single fixed 3/16 inch (4 to 5 mm) disc is the norm. A sharp, well-seated disc and a heavy base matter too, since the base has to stay put under firm pressure. Motor power keeps the disc at speed during a steady push, and working in batches helps whatever the wattage.