Okonomiyaki is said to be originated in Osaka. Yes, I tasted it especially the one with Japanese Spring Onion (Negiyaki).
Okonomiyaki is a pan-fried batter cake and various ingredients. Okonomi means "what you like" or "what you want", and yaki means "grilled" or "cooked".
To have negiyaki, it must be in Kansai (where Osaka is) ... it must be big pile of negi on top of noamal batter and take long time to cook (by chef of course) -- worth waiting ...
The one I poped into is in Dohtonburi, Osaka namely "Houzenji San-Pei". It is the shop where TV Show "Maki's Magic Restaurant" recommend. You can trust her !!!
If you do not remember Mizuno Maki -- check this out : http://www.tbs.co.jp/eng/catalog/english/variety/318.html