Here's a video that shows you how to make it:
1 piece salmon
¼ pack shimeji mushroom
2 tablespoons sake or white wine
1 tablespoon butter
Salt, to taste
Pepper, to taste
Soy sauce, to taste
1. Cut a piece of parchment paper in the shape of a square. Slice the onion thinly. Julienne the carrot. Cut the bottom of shimeji mushroom and tear into bite-sized pieces.
2. Place the salmon at the center of the parchment paper. Season with salt and pepper. Place onion, carrot and shimeji in the order. Sprinkle sake and put the butter on top.
3. Bring up the top and the bottom corner of the paper. Fold the top corner for 3 to 4 times. Twist the ends.
4. Place the salmon packet on a microwave safe plate and microwave for 4 minutes, or cook in 350°F/180°C oven for 20 min.
5. Open the parchment paper carefully and drizzle soy sauce on top.