Thick wide strips of kombu are commonly used to flavour japanese soups noodle broths and stocks dashi kombu contains natural glutamic acid an umami providing amino acid that draws out the taste of other foods to prepare a basic stock add one piece of kombu to a litre of water and bring to a simmer if the kombu is soaked in the water for an hour first it will become tender enough after simmering to slice season and add to vegetable dishes a strip of kombu cooked with helps to soften