Look, I love sensei's stuff, and お好み焼き does mean "cooked as you like", but these descriptions are unlike any okonomiyaki I've ever had, whether Hiroshiman or Osakan.
1a. Osaka base
Get half a Chinese yam or less (nagaimo; check wikipedia), peel if desired, then grate with a ginger/wasabi grater to make snot. Shred cabbage, finely. One egg. Mix! This is Osaka Base.
1b. Hiroshima base
Put shredded cabbage on your stainless cheesesteak grill (griddle) and cover, then top with cooked noodles and cover some more. Maybe some chopped scallions. The eventual serve is flipped; it's a noodle-bottom dish. Other than that, I invite elaboration. I'm not a Hiroshima Base expert; I've only had it once, and it was a little weird for me. Let's go back to Osaka.
2. Put stuff in yer base. Squid? Cooked ground beef? Cheddar? Scallions? Pig's intestine? Da's cool. Just chop it up fine, and Mix.
3. Cook low on your stainless cheesesteak grill or seasoned or no-longer-teflon skillet. Takes a few minutes. Hold on.
4. Flip when solid. As the new side cooks, spread mayonnaise, then お好みサース (yes, very important, and different from とんかつサース, but so is the mayo. And it's really called "okonomi-sauce", which is just awesome). Then remove to your plate, and sprinkle with seaweed flakes 青海苔 (not the big-sheet nori but a kind that tastes ...fresher?) and katsuobushi, which is called bonito, but it makes no difference because bonito does not exist outside of katsuo, while still hot so the planed fishy flakes dance with the convection of your kitchen.
5. Now that you know what you're doing, make the next one for your guest. His/hers will be hotter and better looking than yours, and it won't have fallen apart (cf. Law of Pancakes), and the bonito dance will still be going on.