Step 1

Gather all the ingredients.

Step 2

In a small bowl, combine miso and sake and mix well until miso is completely dissolved. Set aside.

Step 3

Cut the onion into thin slices. If the slices are too thick, they won't be cooked fully.

Step 4

Trim off the bottom of the shimeji and maitake mushrooms and separate them into small chunks.

Step 5

Trim off the bottom of the enoki mushroom and cut it into 2-inch (5 cm) pieces. Discard the stem of shiitake mushrooms and thinly slice them.

Step 6

Trim off the bottom of the king oyster mushrooms and thinly slice them.

Step 7

All the mushrooms should be in similar, bite-size pieces.

Step 8

Cut two sheets of aluminum foil into 14-inches wide by 12-inches long (36 cm by 30 cm). Thinly spread the butter in the center of both sheets. Keep the leftover butter on the side. Divide the onion slices into two sheets, placing them in the center, followed by enoki mushrooms.

Step 9

Then place king oyster, maitake, shimeji, and shiitake mushrooms in piles on each sheet so you can wrap around the mushrooms and seal the top.

Step 10

Divide and drizzle the seasonings over the mushrooms in two packets. Put the leftover butter on top and close the foil tightly so the steam will not escape.

Step 11

Place the two foil packets on a frying pan and cover with a lid (no need to add water). Turn on the stove’s heat to medium for 5 minutes, then medium low heat for 10-15 minutes. If you use fewer mushrooms, your cooking time will be less. Carefully open the foil to check if the mushrooms are cooked through.

Step 12

Alternatively, you can bake at a preheated 425ºF (218ºC) oven for 18-20 minutes. For a convection oven, reduce cooking temperature by 25ºF (15ºC). Carefully open the foil to check the doneness, if you're not sure.

Step 13

Serve the mushrooms while it's hot. Place a generous pat of butter on top (here I use 1 Tbsp of butter for each packet). Drizzle soy sauce and sprinkle chives for garnish if you're using.

Step 14

You can keep the leftovers in an airtight container and store them in the refrigerator for 2-3 days or in the freezer for a month.