Hirayachi is considered Okinawan okonomiyaki, but I think it resembles Korean chijimi (チヂミ in Japanese). The word hirayachi means to “fry flat.” This is a popular snack food and izakaya food, I think because it is simple yet delicious, as well as easy to eat.
It is a pancake type of batter with only a few ingredients: flour, egg, water, salt/pepper, and green onion mixed together, plus a little oil to fry in the pan with. To serve, most people top with shaved katsuobushi (or bonito flakes) and with either Worcestershire, yakisoba sauce, or okonomiyaki sauce (whatever you prefer). I confess that I will typically use Bulldog brand tonkatsu sauce to serve, and add some pickled ginger on the side.