Okonomiyaki is a Japanese dish most accurately described as a savory pancake. A lot of times you may see it described as a Japanese pizza, but I don't think this does it justice. For one thing, it isn't baked like a pizza; it's pan fried like a pancake. And secondly, it isn't a crust with toppings. While it does have toppings, most of the "stuff" is in the batter.
Okonomiyaki translates to "whatever you like, grilled," you can pretty much add whatever you like and leave out whatever you don't like.
Typically, okonomiyaki are rather large and I find it hard to finish, even sharing, a regular sized one. So when I make okonomiyaki, I make them about the size of a generous hamburger.
First prep your onion and cabbage.
Chop the onion and saute it with a little sesame oil until brown.
While the onion is cooking, remove the hard stem portion of 5-6 cabbage leaves and chop. You'll get about 2-2.5 cups.
Once the onion is finished, set the skillet aside. You will use this skillet again in a bit.
In a large mixing bowl, add the flour, baking powder, salt and pepper; whisk gently to combine.
Grate the mountain yam until you get about 1 tablespoon then add to the dry mixture.
Grate ginger (I used pre-prepped grated ginger from a tube) and add to the bowl.
Add the water little by little as you may need more or less to create a batter with the consistency of pancake batter. Whisk to remove all lumps.
Add your chopped cabbage and sauteed onions to the batter.
Wipe the skillet out with a paper towel to remove the oil and put the dried shrimps in the skillet. Heat them over low heat for a few minutes until heated through. Allow them to cool and then crush them into powder.
Crush the nori and crackers.
Add all the crushed ingredients to the batter. Crack the egg, add to the batter, and pierce the yolk. Gently fold the mixture to combine.
I highly recommend using an electric skillet for two reasons. It will allow you to cook more than one small pancake at a time, and it provides even heat which will make cooking easier.
Use a paper towel to coat the bottom of the skillet with a little sesame oil and heat to 225-250F.
Spoon the batter into the skillet and shape into little circular patties about the size of a generous hamburger. Top them with the bacon pieces.
Cover the skillet and cook for about 5-7 minutes.
(Covering the skillet keeps the heat and steam inside and requires less cooking time. The trapped steam will cook the cabbage, although the cabbage will have a sort of al dente texture when the okonomiyaki are finished.)
Flip the okonomiyaki, increase the heat to about 300F, and cook an additional 5-7 minutes, covered.
After you flip okonomiyaki and before you cover the skillet, you can coat the cooked side with a little okonomiyaki sauce while the bacon side is cooking. This way the sauce will cook into them. Use a brush or your spatula to spread the sauce.
Once they are finished cooking, plate and top with mayonnaise (I recommend Japanese mayonnaise. An extremely popular brand is Kewpie.) and more okonomiyaki sauce. They are best eaten while still hot. This recipe will make about 6 small okonomiyaki.
A Note About the Mountain Yam:
Mountain yam can be difficult to find if you don't have access to an Asian grocery.
It doesn't impart any sort of taste to the okonomiyaki, but acts as a binder and gives the okonomiyaki elasticity. I have made okonomiyaki with and without the mountain yam, and I can tell the difference. Without it, the okonomiyaki are sort of loose. And with the yam, they hold together better and are easier to flip.
However, if you can't find mountain yam, skip it. It's not a big deal. Plus, making smaller okonomiyaki will make them easier to flip anyway.
*UPDATE: I've recently learned that sweet potato, yam, or russet potato can be used to substitute mountain yam but I have not tried using them. All of these things are more moist and not nearly as gooey as mountain yam.