Do I need to make horizontal cuts when dicing an onion?

For a fine or medium dice (¼ inch or smaller), yes — horizontal cuts give you even cubes. Skip them for a rough ½-inch dice; the onion's natural layers do enough of the work on their own.

Why do my onion layers keep slipping apart when I try to dice?

You removed the root too early. Keep it fully intact until the final crosscut — it acts as a clamp that holds every layer in place. Discard the root end only at the very end.

What is the difference between dicing and mincing an onion?

Dice means pieces ¼ inch or larger — distinct chunks that hold their shape in the pan. Mince means pieces under ⅛ inch that melt into the dish. Both use the same three-cut method; mincing just needs much closer, tighter passes.

Kitchen tips · knife-skills

Dice an onion in three cuts — the restaurant way.

Three cuts, one rule — keep the root — and you'll get a consistent dice every time.

Master of Meat · The Restaurant Cook

August 2, 2026 · 2 min read

Halve the onion root-to-tip. Peel it. Set it cut-side down on the board.

Keep the root intact. That small nub at the base holds every layer together for all three cuts. Lose it early and you spend the rest of the prep chasing loose rings around the board.

The Three Cuts

1. Horizontal cuts (fine dice only)

Rest your non-knife hand flat on the onion. Make 2–3 cuts parallel to the board, stopping 1 cm short of the root. Do not cut through.

Skip this step entirely for a ½-inch dice. The onion's natural layers already do the work.

2. Vertical cuts

Slice downward, spacing cuts to match your target size. Fan them slightly toward the root — they converge there, which gives cleaner corners than strictly parallel cuts do. Keep the root intact throughout.

3. Crosscuts

Slice across from the tip toward the root end. The dice falls away as you go. The root end is scrap — discard it.

Size at a Glance

Dice	Spacing	Common use
Fine (⅛ in)	3 mm	Soffritto, sauces, mirepoix
Medium (¼ in)	6 mm	Soups, stews, rice
Large (½ in)	12 mm	Stir-fries, roasted vegetables

Three Mistakes Worth Avoiding

Cutting off the root first. The most common error. Everything else here is secondary to this one.

Uneven vertical spacing. Closer cuts on one side means smaller pieces that overcook before the larger ones finish.

Lifting the knife heel. Keep the tip on the board and rock the blade forward through the cut. Faster, safer, and more control throughout.

Three cuts. One rule. A sharp knife makes it easy.

Common questions.

Do I need to make horizontal cuts when dicing an onion?: For a fine or medium dice (¼ inch or smaller), yes — horizontal cuts give you even cubes. Skip them for a rough ½-inch dice; the onion's natural layers do enough of the work on their own.
Why do my onion layers keep slipping apart when I try to dice?: You removed the root too early. Keep it fully intact until the final crosscut — it acts as a clamp that holds every layer in place. Discard the root end only at the very end.
What is the difference between dicing and mincing an onion?: Dice means pieces ¼ inch or larger — distinct chunks that hold their shape in the pan. Mince means pieces under ⅛ inch that melt into the dish. Both use the same three-cut method; mincing just needs much closer, tighter passes.

About the author

Master of Meat — The Restaurant Cook

Writes about techniques, doneness, knife skills, timing, and heat control. Tone: direct, brief, no-nonsense.

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