Wash spinach thoroughly and cut into appropriate sizes.

Prepare anchovy broth by removing the heads and guts of anchovies, lightly roasting them, and simmering with kelp in 8 cups of water for 10 minutes. Strain the broth.

Prepare clams by soaking them to remove sand.

Wash and shred oyster mushrooms, slice green onion, chop onion, and prepare minced garlic.

Add strained broth to a pot and bring to a boil. Add clams and cook until they open. Remove clams immediately to prevent overcooking.

Set aside cooked clams in a bowl with a small amount of broth to keep them moist.

Strain the broth again and return it to the pot. Dissolve miso paste into the broth using a strainer.

Add minced garlic to the miso broth and bring to a boil.

Add spinach and onion to the boiling broth and cook briefly. Then add oyster mushrooms and green onion.

Finally, add the cooked clams and their reserved broth to the pot. Simmer briefly and adjust seasoning with soy sauce if needed.