Japanese style poached salmon

For ➍
600 g skinless salmon filets
150 g portobello mushrooms, finely chopped
3 tbs finely chopped yellow onions
20 cl mirin, sake or dry white wine (or add some water)
15 cl heavy cream*
2 tbs butter*
1 tsp fresh (or ¼ tsp dried) tarragon, finely chopped
¾ tsp salt
¼ tsp pepper

Rinse salmon and pat dry with a paper towel. Cut filet into 4 equal portions.
In large skillet, arrange mushrooms and onions covering bottom of pan. Place salmon pieces on top.
Pour sake and water over salmon and bring to a boil over medium-high. Cover, reduce heat to medium-low and gently simmer 3-5 m or only until salmon is slightly undercooked. Remove salmon from pan, transfer to a plate, cover with tin foil, and set aside.
Increase heat to medium-high and continue to boil mushrooms and onions until the liquid has reduced to 40 cl.
Add any extra juices from salmon plate, stir in heavy cream*, butter*, tarragon, salt, and pepper. Reduce heat to medium and continue to cook 10-15 m until liquid has reduced to 10 cl. Season with salt and pepper to taste. Remove sauce from heat and set aside.

Transfer salmon to individual serving plates, spoon mushroom reduction sauce on top of salmon. Serve immediately.

*Omit cream and butter.