Begin by rinsing the sushi rice under cold water until the water runs clear to remove excess starch. Drain the rice well and set it aside.

In a medium saucepan, combine the rinsed sushi rice with water at a 1:1 ratio. Bring to a boil, then reduce to low, cover, and simmer for 18-20 minutes until tender.

Remove from heat and keep covered for an additional 10 minutes. Fluff the rice gently with a fork.

In a large skillet, heat vegetable oil over medium heat. Add the sliced shiitake mushrooms and sauté for 5-7 minutes until golden brown.

Stir in minced garlic, grated ginger, white miso paste, soy sauce, and sesame oil. Cook for 2-3 minutes, stirring frequently.

Pour the mushroom mixture over the prepared sushi rice and gently fold together with a spatula.

Press the rice mixture into an even layer in the skillet and cook over medium heat for 10-15 minutes until the bottom is crispy.

Remove from heat and serve immediately, garnished with chopped green onions and sesame seeds if desired.