Dice an onion right and the rest of the board gets easy

Cut the onion pole to pole, not around its waist. That one decision does more for your dice than any knife you could buy.

Here's why it works. An onion is built in curved layers that run from root to tip, and the root end holds every one of those layers together like a staple. Halve it through both ends, peel, lay a half flat side down, and you've got a stable object with a built-in handle. Now you make three cuts and you're done: lengthwise slices aimed at the root, then crosswise slices, and the dice falls apart on its own.

An eight-inch chef's knife does all of it. A Victorinox Fibrox costs less than most people spend on a steak dinner and will outwork a knife at four times the price, provided you keep it sharp. We'll get to that.

The three cuts, in order

Trim the stem end off. Leave the root attached. Stand the onion up and split it through the root, then peel back the papery skin and the first slippery layer underneath, because that layer never dices cleanly anyway.

Flat side down. Always flat side down. A rolling ingredient is how people get stitches.

Now slice lengthwise, tip of the knife pointed at the root, stopping about a quarter inch short so the whole thing stays hinged. Fan your cuts slightly, aiming each one at the root rather than driving them all straight down. The layers curve, so the cuts should too. Then turn the onion and slice across. Even dice, no horizontal cut required.

You'll read that you need that horizontal cut, the one where you run the blade sideways through the onion parallel to the board. For a very fine brunoise on a big onion, sure. For weeknight cooking it's the single most dangerous cut in the sequence and it buys you almost nothing. Skip it.

When you reach the root, stop. That last inch is fibrous and it goes in the stock bag.

Your left hand is the ruler

Right hand holds the knife. Left hand decides how thick everything is, and most people never think about it.

Curl your fingertips under so the first knuckles stick out ahead of the nails. Rest the flat of the blade against those knuckles. Now the blade physically can't reach your fingers, and you set thickness by how far back you walk that hand between cuts. Small steps, thin slices. That's the whole system.

The knife hand should pinch the blade, not grip the handle. Thumb and index finger on the flat of the steel just ahead of the bolster, remaining three fingers wrapped around the handle. It feels wrong for about a week. Then it feels like the knife grew out of your arm.

And stop chopping straight down. A chef's knife cuts on the glide. Push the blade forward and down through the onion, or pull it back and down, letting the curve of the edge do the work. Straight down is how you crush a tomato and how you get that squeaky crunch that means you're bruising more than cutting.

What actually makes you cry

Sharpness and the root. A dull blade ruptures more cells, which releases more of the compound that gasses you. And the root end holds the highest concentration of it, which is another reason to leave it intact until the end.

Fifteen minutes in the fridge before you cut slows the reaction down noticeably. Running the exhaust fan helps more than people expect. Contact lenses help too, though that's a strange thing to plan a dinner around.

What doesn't work: breathing through your mouth, a candle, holding a spoon in your teeth. You've been lied to.

The knife is dull. Yes, yours.

Hold a sheet of printer paper by one corner and draw the blade down through it. A sharp knife takes a clean ribbon off. A dull one snags, folds, or tears the sheet. Most home knives tear the sheet.

A honing rod doesn't sharpen anything. It straightens an edge that's rolled over microscopically, which is real and useful, and you should give the blade six passes a side every few uses. But steel wears away. Eventually you need abrasive.

Two honest options. Buy a 1000-grit whetstone, watch someone do it, and spend twenty minutes learning a consistent angle, roughly the thickness of two quarters under the spine. Or find the guy at the farmers market or the hardware store who sharpens for a few dollars a blade and hand him your knife three times a year. The second option isn't cheating. A sharp knife you didn't sharpen still cuts.

Two things that kill edges fast: glass cutting boards and the dishwasher. Use wood or plastic, wash by hand, dry it immediately.

Put a damp paper towel or a folded dish towel under the board. A board that slides is a board that's about to teach you a lesson.

Everything is one flat side away from easy

Once the onion clicks, the rest of the board follows the same law. Make a flat side, put it down, then cut.

Carrots. Trim both ends, halve lengthwise, flat side down. Now it can't roll, and you can plank, batonnet and dice in that order. Same for parsnips and potatoes.

Bell pepper. Don't wrestle the core. Stand it up and cut the four walls off around it, leaving the seed pile standing. Lay each wall skin side down, flatten it with your palm, and slice.

Tomato. Skin side up, and let the tip of a sharp blade start the cut. A dull knife skates across tomato skin and then buries itself in whatever's behind it.

Garlic. Smash with the flat of the blade, skin peels off in one piece, then rock-chop. A pinch of kosher salt on the board gives the blade traction and keeps the paste from gluing itself to the steel.

Herbs. The reason your parsley turns black and sad is that you chopped it forty times. Cut it once, cleanly, and walk away. Basil goes in a stack, roll it into a cigar, slice across into ribbons.

Meat. Find the grain, the direction the muscle fibers run, and cut across it. Flank steak sliced with the grain is jerky. Sliced against it, the same steak is tender. Twenty minutes in the freezer firms up anything you're trying to slice thin.

Get good in a month

Buy a five-pound bag of yellow onions. Dice all of them over two weeks, one or two at a sitting, and freeze what you don't use in a zip bag. Your dice will be ugly for the first four. Around the seventh you'll stop looking at your left hand. Around the twelfth you'll notice you're talking to someone while you do it.

One rule that never bends: if the knife goes off the counter, step back and let it hit the floor. Never reach.

That's the whole skill. A flat side, a curled hand, an edge that bites. Learn it on onions because onions are cheap and forgiving, and because every good dinner you'll ever cook starts with a pile of them in a pan.