Cider-Poached Fish - cooking recipe

Ingredients

2 -3 shallots (or 1/4 small onion)
5 ounces mushrooms, such as portobello, button, cremini
1 1/2 - 2 lbs white fish fillets, such as black cod, haddock, halibut or 1 1/2-2 lbs tilapia fillets
1 cup dry sparkling apple cider
2 tablespoons unsalted butter, plus
2 tablespoons unsalted butter, for swirling in at the end (optional)
3/4 cup creme fraiche (optional)
salt & freshly ground black pepper

Preparation

Peel and mince the shallots.
Stem and wash the mushrooms, then coarsely chop, should yield 1/2 - 3/4 cup.
Cut the fish into 2 or 4 equally sized pieces, if necessary, so that they fit comfortably in a large skillet.
Melt 2 tbsps of the butter in a large skillet, preferably non-stick, over medium-low heat. When it is foamy, add the shallots and cook, stirring occasionally, for 5-7 minutes, until they are transluscent.
Season the fish lightly on both sides with salt and pepper. Arrange the pieces in the skillet in a single layer.
Cook for 1-2 minutes, then add the mushrooms, stirring to combine.
Add the cider, increase the heat to medium or medium-high so that bubbles appear at the edges of the skillet.
Cover and cook for 8-10 minutes; turn the fish pieces over halfway through, if desired.
Transfer the fish to a deep serving dish to keep warm, leaving the liquid in the skillet.
Increase the heat to medium-high, if needed; cook uncovered for 2-3 minutes to reduce sauce slightly. Taste and adjust the seasoning as necessary.
(At this point, if you want to make a richer sauce, remove the skillet from the heat. Add the creme fraiche or butter and stir to incorporate.).
Spoon the sauce over fish.
Serve immediately.