In a small bowl, combine the soy sauce, salt, sugar, white pepper, Worcestershire sauce, and sesame oil.
Take your cooked rice and fluff it with a fork.
Heat a pan over medium high heat, spread oil around and add the white portion of the green onions. Stir-fry for about 1 minute, until the onions are beginning to turn translucent. Add the button mushrooms. Stir-fry for 1 to 2 minutes, or until the mushrooms are lightly browned and caramelized.
Add the rice. Using a spatula to stir-fry it and break up any clumps.
Once the rice is warmed, stir up the sauce mixture and pour it over the rice. Immediately mix with a scooping motion to evenly coat the rice. Top with green part of green onions and serve!