Prepare oatmeal, tuna, and seaweed.
Soak dried seaweed in water and cut it into bite-sized pieces.
Pour water into a pot and add the seaweed. Bring to a boil.
When the seaweed becomes soft, add tuna and oatmeal.
Simmer over medium-low heat, stirring occasionally.
Season with salt to taste.
Once the porridge thickens, serve in a bowl.