In a dutch oven or similar type of thick pot with a lid, add the water, soy sauce, and frozen spinach. Put the lid on and simmer the mixture over low heat for a couple minutes until the spinach has thawed completely. Stir to break apart the spinach.

Season fish with a pinch of salt.

Add ginger and green onion whites to the pot, then add the mushrooms, then top with the fish.

Cover the pot and steam the fish 6-8 minutes until fully cooked. Top with sesame oil and green onion greens and serve.

Mix ingredients in a bowl and serve.

For leftovers you can simply mix all the ingredients in advance and store in a tupperware in the fridge and then just serve and dress each time you eat.