Chop the kimchi into bite size pieces and shred the flat cabbage quite thinly.
In a bowl, mix the buchim garu (flour mix) with water, egg and a teaspoon of sesame oil.
Thinly slice the spring onions and add them to the batter with the cabbage and the kimchi.
Heat a pan on medium high heat with a good amount of vegetable oil. Add the mixture and cook for about 5 minutes.
Flip over and cook again for 5 minutes.
Flip over one last time, cover, bring the heat down to medium and cook for another 5-8 minutes, checking regularly to see if the okomiyaki is cooked through.
Serve on a large plate and drizzle on top some mayo and Tonkatsu sauce. Finish with shredded roasted seaweed and sesame seeds.