This recipe is made so that even kids who live outside Japan can cook delicious okonomiyaki. If you're in Japan, though, you can easily buy okonomiyaki powder and sauce; all you have to do to make the batter is mix the powder with eggs and ingredients. Okonomiyaki has several variations.
(The Japan Forum)
Okonomiyaki: A type of teppanyaki, or food fried on a very hot metal plate. Originally made by frying a simple batter of flour and water, it took on the name okonomiyaki (okonomi means "as you like," and yaki means "fry") after meat and vegetables came to be added.
(The Japan Forum)
Hiroshima-style okonomiyaki: In Hiroshima, okonomiyaki is made without mixing the batter and other ingredients before frying. Instead, ingredients like cabbage and bean sprouts are spread over the batter. The pancakes are then placed over yakisoba noodles, and the side with the yakisoba is bound together with egg to finish. This style of okonomiyaki was invented in Hiroshima.
Monjayaki: A food that is very popular in Tokyo's old downtown but is also seen in other parts of the Kanto region. The consistency is gooey, as the flour is mixed in plenty of water. The ingredients are cooked first, then shaped into a ring, and the batter is poured into the center. After the batter and ingredients have been mixed together, the monjayaki is eaten directly from the griddle by scooping up bits with a small spatula.
((c) Osaka Convention & Tourism Bureau)
Takoyaki: Balls of about 3 cm to 5 cm each that are made by cooking a batter with octopus pieces, spring onion, and pickled ginger in a special pan with semispherical molds. They're usually eaten with sauce. Takoyaki was born in Osaka, but nowadays it's commonly sold at festival stalls across Japan.