Finely chop the onion and soak the shiitake mushrooms if using dried ones.

Mash the tofu thoroughly with the back of a knife until smooth.

Heat sesame oil in a pot over medium heat and sauté the chopped onion until translucent.

Add the broth to the pot and bring it to a boil. If using water, add powdered broth for flavor.

Add the cooked rice to the boiling broth and cook on high heat until the rice starts to break apart.

Add the mushrooms and mashed tofu to the pot and continue cooking.

Season with soy sauce and fish sauce, then reduce to low heat and simmer until the porridge reaches your desired consistency.