Cut salmon to bite size pieces.
Slice 2 onions in ½” pieces.
Slice 1 leek in ¼” pieces.
Peel 3 potatoes.
Cut potatoes in 3-4 pieces.
Soak in water.
Place kombu in 5 cups of water.
Heat water to boiling point.
Remove kombu as water boils.
Remove any leftover pieces from water.
Add potatoes and onion.
Cover with lid and cook on medium for 5 minutes.
Skim off foam with ladle.
Add leek.
Cook for 3 minutes or until potatoes are cooked.
Add salmon.
Cover and cook for 2-3 minutes.
Mix 3 tablespoon of miso with 1 tablespoon of mirin.
Add mix to pot.
Add 1 tablespoon of butter.
Serve.