Cut the mushrooms into easy to eat pieces. Slice the onion. Prep 2 large sheets of aluminum foil.
Spread one of the sheets and place half the amount of onions in the middle. Add 2 scallops, and top with 1/2 the mushrooms. Season with salt and pepper, and top with 2 knobs of butter.
How to close up the foil packets: hold the top edges, sprinkle the sake (so that it doesn't leak out) and fold 2 to 3 times. Fold the left side to the right 2-3 times, and fold the right side in the same way.
Place both foil packets on a pan, and cover with a lid. When it starts steaming, turn down the heat to low, and steam cook for 10 minutes.
Story Behind this Recipe
My husband always requests, "please cook scallops in foil!".
Be careful not to burn yourself when opening the foil packets. If the contents are a little burned it's fine. Add some soy sauce or ponzu sauce to taste and enjoy.