I was thinking leave the onions on the blade for a while look. Or just put your tennis shoe on the blade with mustard. (jk, looks cool)
Chewie's the man.
Good idea, and could give you a really nice geometrical pattern.
I actually did that by accident with my new Yamawaku gyuto. I cut up some onions and left the juice on the blade for a few minutes. When I went to clean it, there was this pattern of discoloration. I panicked and scrubbed it off, before I realized what it was. Duh. It began as a dull reddish brown (kind of looked like rust, which is why I panicked), but underneath it was a pretty, almost iridescent blue. From the pics, it looks like that's a color that a lot of folks shoot for. The next morning, I took the chopped up onions out of the fridge (I was prepping the night before), and buried the blade in them. But, this time there was very little change. So, I think it works best with fresh-cut, juicy onions. Don't let them dry out at all.
Waiting for the next time I chop some up to try again. And, BTW, it was somewhat of a geometric pattern.
THAT was the equation. EXISTENCE!...SURVIVAL..must cancel out..programming!
It's not my knife, but I thought I'd share a pic of the patina on Son's Dragonslayer gyuto.
Almost don't want to post with some of your guys amazing colors, but new phone is still fun to play with so here it goes.