Cut the naganegi diagonally into 1 cm long pieces.Slice the shiitake mushrooms on an angle.
Heat a pan to medium-high and add the oil. Add the negi and stir-fry for 1-2 minutes til it starts to brown, then add the shiitake. Stir-fry until slightly softened, about 3-4 minutes.
Add the soy sauce and sake and stir-fry to mix for another 30 seconds. Turn off the heat and serve!