Step 1 Heat the oil in a nonstick skillet over medium-high heat. Add the onion and ginger root and cook until the onion is tender, 2 to 3 minutes. Raise the heat to high, add the mushrooms and cook until they start to soften, about 2 to 3 minutes. Add the soy sauce and sugar and cook, stirring, until the mushrooms are tender, 5 to 6 minutes.