making the single horizontal cut first makes every vertical cut after more difficult to perform without harming the structure of the onion.
technique and a sharp knife enable the horizontal cut second to be vastly superior to doing it first.
I'm not sure I understand. My knives are razor sharp (I keep a Shapton 1000 and 4000 on my counter along with a strop, my daily driver is a carbon steel I have to wipe down every time I cut a vegetable). They sail through the onion, but the sliced-up onion still splays out to both sides when I make the horizontal cut, and if you watch cooks doing it, it happens there too. What harm am I doing to the structure of the onion by doing it in the "wrong order"? They're the same cuts. The difference seems to be that in my order, the onion stays more stationary.
Don't get me wrong, I'm sure there's a reason everyone is doing it this way, because it's kind of clearly more annoying than the way I'm doing it?
(I'm just nerding out on this).
Here's the way I'm thinking about this:
the vertical cuts do not significantly the internal structure of the onion as each individual cut I make does not entirely sever the connection between the thin vertical slices I'm making. This means that I can do a lot of these, and not worry about harming the overall structural integrity. Then I make a single horizontal cut which does harm the overall structural integrity. This is not intrinsic to the horizontal cut itself, but the fact that I have both horizontal and vertical cuts.
If I start with the horizontal cut, again I do not signficantly harm the structural integrity of the onion. However, each subsequent vertical cut I make is now going to individually compromise the integrity of the onion.
With a sufficiently sharp knife, the single horizontal cut at the end does not really pose a significant danger overall.
This all being said I almost never do the horizontal cut out of pure laziness, and instead prefer to just do angled vertical cuts analogous to the video. They're never perfect but fine enough for me...
I still don't get why you need the horizontal cut at all. The diagram at the bottom of the blog post shows how unnecessary it is when you do the vertical cuts at a narrow range of angles like that (which I have been doing for a while now).
The point of Kenji's method (really, all radial-ish methods, but radial is strictly worse) is that you don't have to do the horizontal slice. If you slice vertically, you do --- you can see it for yourself, if you don't the dice from the edges of the onion are almost twice as big as the diece from the center.
I’m sure I’ve seen a clip of some tv chef saying it is unnecessary. Maybe Jacques Pépin but not sure.