How to Dice an Onion

30-second preflight — all three checks must be YES.

Firm onion · sharp knife · stable board · bowl and towel ready.

A dull knife or a wobbly board turns a simple cut into a slip — checking tools first keeps every later cut controlled.

1. Onion ready? Firm yellow or white onion with dry outer skin — not soft or moldy.
2. Tools out? Sharp chef's knife (or 7–8" knife), cutting board that does not slide, bowl, towel.
3. Board safe? Board flat on the counter; put a damp towel under it if it skates.

All three checks are YES — you are ready to trim the stem end in Step 1.

Eyes already watering just from holding the onion? → Tearing eyes.

Trim about ¼ inch off the stem (top) end — leave the root on.

Cut ~¼ inch off the stem tip only; hairy root stays attached.

Removing only the stem gives you a flat starting face while the root still holds layers together for even cuts later.

1. Set the onion on its side on the board so the stem tip faces you clearly.
2. Hold with a claw grip — fingertips curled under, knuckles leading.
3. Slice about ¼ inch (6 mm) off the stem tip; do not cut the root yet.

The stem end is cut flat and the root with its hairs is still fully attached.

Halve the onion through the root, then peel the outer skin.

Stand stem-down or on a flat face → cut through root → peel dry skin.

Cutting through the root keeps each half held together at the hinge so you can peel and slice without the layers falling apart.

1. Place the onion so you can cut from the stem face straight down through the root.
2. Cut firmly into two equal halves.
3. Peel off the dry papery skin (and any tough outer layer) from each half.

You have two peeled halves, each still connected at the root hinge.

Put one half flat-cut side down so it sits steady.

Flat face against the board — half should not rock when you press lightly.

A curved face will rock under the knife and send the blade toward your fingers — the flat cut is what makes controlled dicing possible.

1. Place one half cut-side down on the board.
2. Press lightly with your fingertips — it should feel planted, not tippy.
3. If it rocks, remake a thin flat cut on that face before continuing.

The half sits steady flat-side down with the root end facing sideways for the next cuts.

Still rocking or the knife starts to slip? → Onion slipping.

Make 1–2 horizontal cuts toward the root — stop short of the root.

1–2 parallel horizontal cuts; blade stops before the root hinge.

Horizontal cuts create the layers of the dice — stopping before the root keeps the onion from falling into loose sheets.

1. Curl your guide hand into a claw; knuckles face the blade.
2. With the knife parallel to the board, cut 1–2 horizontal slits from the stem side toward the root.
3. Stop about ¼–½ inch before the root so the hinge stays connected.

You see 1–2 clean horizontal slits and the root still holding the half together.

Tears making the board hard to see? → Tearing eyes.

Make even vertical cuts toward the root — still leave the hinge.

Even vertical cuts ~¼–½ inch apart; stop short of the root.

Vertical cuts set the width of each cube — the intact root is what keeps those strips lined up for the final cross-cuts.

1. Keep the claw grip; never point fingertips at the blade.
2. Cut straight down in parallel lines about ¼–½ inch apart from stem toward root.
3. Again stop short of the root so strips stay attached.

The half looks like even strips still joined at the root end.

Onion starts sliding or rocking mid-cut? → Onion slipping.

Cross-cut across the half into dice, then discard the root nub.

Slice across into cubes, then trim off and discard the root end.

These final perpendicular cuts turn the held-together strips into cubes; trimming the root last removes the tough nub after it has done its job.

1. Rotate the half if needed so you slice across the strips.
2. Cut into dice about ¼–½ inch wide, matching your earlier spacing.
3. When you reach the root, trim it off in one piece and discard (or compost).

A pile of onion cubes sits on the board and the tough root nub is gone.

Big mix of large chunks and skinny shards? → Uneven dice.

Repeat the same cuts on the second half.

Flat down → horizontal → vertical → cross-cut on the other half.

Repeating the same sequence keeps both halves consistent so the whole onion cooks evenly later.

1. Place the second half flat-cut side down.
2. Repeat Steps 4–6: horizontal, vertical, then cross-cut.
3. Discard the second root nub the same way.

The entire onion is diced into one pile of cubes.

Scoop the dice into a bowl and wipe the board.

Move cubes to a bowl; wipe peels and juice off the board.

Getting dice off the board right away keeps them from drying out or picking up loose peel bits and excess juice.

1. Use the flat of the knife or a bench scraper to push dice into the bowl.
2. Push peels and the root nubs into trash or compost.
3. Wipe the board with a towel so it is dry and clear.

Dice are in the bowl and the board is wiped clean of peels and scraps.

Rinse your hands and the knife, then dry the knife.

Rinse onion juice off hands and blade; dry the knife completely.

Onion juice on skin and steel stings and rusts — a quick rinse and dry finishes the job safely.

1. Rinse your hands under cool water; pat dry.
2. Rinse the knife carefully under running water, keeping fingers clear of the edge.
3. Dry the knife fully with a towel before putting it away.

Hands are rinsed and the knife is clean and dry.

Spot-check: most pieces are roughly the same size.

Most cubes look about ¼–½ inch — ready for the pan or recipe.

Even size means the onion browns and softens at the same rate instead of burning small bits while big chunks stay raw.

1. Look into the bowl — most pieces should look roughly similar.
2. If a few large pieces remain, re-cut only those (see the uneven branch if many).
3. Your diced onion is ready to cook.

Most dice are roughly even (~¼–½ inch) and ready for cooking.

Lots of uneven pieces? → Uneven dice.