Butadon (豚丼) means "pork bowl", and the version from Obihiro in Hokkaido is famous across Japan: thin pork slices charred in a pan, then lacquered in a sweet, smoky soy glaze and laid over hot rice.
It's simpler than gyudon and very forgiving. The sauce is equal parts soy sauce, mirin and sake with a little sugar, reduced until sticky.
Ask your butcher for thinly sliced pork shoulder or belly, or look for shabu-shabu or hot pot pork at an Asian grocer.
