Preheat your Traeger grill to 225*
Season the Zabuton steak on all sides with a blend of salt and pepper
Put the steak in the preheated grill and cook for about 30 minutes at this lower temperature
While the steak is cooking, make the sauce by combining the remaining ingredients except sesame seeds in a grill-proof saucepan
Place the sauce on the grill to cook while the steak continues cooking
When the steak has reached the desired internal temperature of 125*, remove the steak and the saucepan from the grill and increase the temperature to 400*
When the grill gets hot, place the saucepan back in the grill
Sear the steak on all sides for about 60 seconds per side
Allow the pan to get hot and the sauce to bubble, reducing slightly
Pull the steak from the grill, tent with foil and allow to rest for 5 minutes
Carefully remove the saucepan from the grill and let it cool briefly
Transfer the sauce to a serving dish and sprinkle generously with sesame seeds
Cut the steak against the grain and serve with yakiniku sauce for dipping