In a small bowl, beat egg and water and set aside.
Melt butter in large wok or sauté pan over medium heat and add mushrooms.
Sauté mushrooms for 2 minutes, stirring occasionally.
Add the rice, chopped chicken, and green onion.
Cook, stirring often, for 6 minutes.
Push the rice mixture to the side of the wok or skillet and add the olive oil.
Add the eggs and scramble until thickened.
Stir the rice mixture and the scrambled egg together until combined.
Add coconut aminos or soy sauce, salt, black pepper, and cayenne pepper and stir until mixed thoroughly.
Garnish with sesame seeds and additional chopped green onions, if desired.