Slice the mini tomatoes and onion into bite-sized pieces.

Rehydrate the dried wakame in water for 5 minutes, then drain.

Bring 300ml of water to a boil and add the granulated dashi.

Add the sliced onion to the boiling broth and cook until tender.

Add the mini tomatoes and rehydrated wakame to the broth.

Turn off the heat and dissolve the miso into the soup using a ladle.