So many instructions to cut an onion are essentially
- Cut off the top
- Peel
- Cut in half
- Cut horizontally (in parallel to the cut you just made)
- Cut vertically into strips from just shy of the bottom to top, with the bottom holding things together
- Cut vertically perpendicular to your last cuts to get little squares
On something like a potato, I'd understand it. You'll be cutting a 3-dimensional object along all 3 axes to get cubes. But as Shrek taught me, onions have layers. Why make that first set of horizontal cuts when the onion's natural layers do the same thing already, albeit a little bit curved?