Keep the pan on medium-high heat and add the sesame oil.
Add the green onions and stir-fry until evenly coated with oil. Add the sliced shiitake and stir-fry until evenly coated with oil. Add the minced garlic and stir-fry until evenly coated with oil.
Add the rice and break-up the chunks of rice. Stir or toss the rice without mashing it.
When rice is coated with oil, add the diced chicken and stir well without mashing the rice.
Add the prepared egg and break into small pieces.
When all the ingredients are mixed well, add soy sauce, salt, white pepper, and freshly ground black pepper. Stir or toss the rice and mix it all together.