Guides
Slice an onion: make even half-moon slices
To slice an onion, rest each half flat, work at your own pace and prepare the next ingredients before heating, without trying to match a demonstration’s speed.
Slicing an onion here means making thin strips rather than dice. For soup or sauce, aim mainly for similar thickness from one slice to the next. Begin on a stable board with the hob off: preparation and cooking each get their own moment.
Rest each half on its cut side
Remove the dry skin and stem end. Halve the onion along the stem-to-root axis and rest a half on the cut face. If the bulb slips or the cut becomes hard to control, stop and find a stable position again.
Hold the onion with curled fingers, away from the cutting edge and outside the blade’s path. The chef’s knife guide helps set up the workspace. Keep your own pace: a demonstration’s speed is not a target.
Cut half-moons
With the half resting flat, make successive thin cuts across the stem-to-root axis to form half-moons. Move the supporting hand gradually, keeping fingers away from the blade. Horizontal incisions used for dicing are not needed here.
Stop when the remainder is too small to hold without bringing fingers close to the edge, then set that end aside. Repeat with the other half. Slightly thicker, controlled slices are preferable to thinness achieved with an unstable movement.
Transfer before switching on the heat
Move the slices with a spatula or scraper without dragging the knife edge over the board. Clear the workspace and prepare the next ingredients. The guide to softening an onion then takes over for the soup or pasta.
If handling a knife is difficult, learn the movements with guidance. Speeding up does not solve a grip problem.
Sources for this page
- Good Food : Slicing an onion, méthode en demi-lunes , Accessed October 22, 2026
