I've been holding off plagiarising this recipe from Eat Your Kimchi because I wanted to support the creators. Unfortunately it looks like their blog site's gone off the air some time since I last looked at it, so it's "Yo-ho, yo-ho, a pirate's life for me!"
Basically okonomiyaki is a Japanese cabbage fritter. The EYK video covers the Osaka-style in that it has pork-belly strips on the A-side. I might as well add some of my own "as you like it" changes along the way to make it look like I didn't just copy the recipe outright.