Place the tuna in a strainer to remove the oil.
Wash the rice thoroughly and soak it for about 30 minutes.
Put the soaked rice and water in a pot and bring it to a boil.
Stir and cook over medium-low heat until the rice softens and expands.
Add the tuna and season with salt.
Once the porridge thickens, transfer to a bowl and top with chopped green onions.