Cook the rice according to your rice cooker instructions and allow it to cool down.
Measure each rice bun to 80 g (2/3 cup) and using cling wrap, make the rice ball then flatten them by pressing into a mold to 1cm thick. Set aside. Make 4 rice buns. *2
Slice the beef very thinly. *3
Combine all marinade ingredients (soy sauce, sugar, sesame oil, tobanjan, miso paste, and sesame seeds) together in a bowl and marinate the thinly sliced beef for about 20 minutes.
Heat 1 tbs of sesame seed oil in a frying pan over medium heat and cook the marinated beef till the beef is brown.
Heat a non-sticking frying pan over medium heat and brown the surface of rice buns by first brushing with soy sauce. When the rice surface is browned and hardened a little bit turn the heat off.
Place the bottom rice bun on a plate and top with lettuce leaves. Place the beef on top of the lettuce and top with another layer of lettuce. Place another rice bun on top of it.
Serve with Renkon Chips and enjoy
*1 As stated in the post, if you can not access sweet rice, you can add Katakuriko (potato starch) 1 tbsp after the rice is cooked. *2 If you don't have a large cookie cutter (about 4 inch/11cm), you can flatten and shape the rice with cling wrap. *3 I bought already thinly sliced beef from a local Japanese grocery store. If you can not get thinly sliced beef from any Japanese/Korean butchers, you can slice it yourself. When the meat is half frozen, slice it thinly with a sharp knife.