Oven Poached Salmon with Spinach Butter Sauce
Have you ever heard of wild sea spinach? I hadn’t until I read about it in, The Forgotten Skills of Cooking, by Darina Henry. Wild sea spinach grows along the coastline of Ireland, and other countries in the UK. Another species of wild spinach grows in New Zealand and parts of Asia. Sea spinach is related to most cultivated beets. However, casting family lines aside, prepare sea spinach the same way as cultivated spinach. Darina has made me so curious about wild sea plants. I wonder how they taste and if they are salty from being bathed by the sea.
Anyway, I saw a recipe of hers where she prepares wild sea spinach in a butter sauce and serves it spooned over oven poached sea trout. Maybe I am a romantic at heart, but the idea of cooking vegetables and fish from the local coastal area made me want to jump into the cookbook and be there. If you read my post about crispy potato skins, you know about my fantasy wanting to forage wild plants with Darina. It is very possible this recipe could have been the one that got my fantasy in full gear.
In Darina recipe, she poaches a whole sea trout “en papillote”. This is a technique where you wrap fish in foil or parchment paper and bake it in the oven. I love to prepare fish using this technique. The fish is very moist and the natural juices accumulate in the pouches. I have never poached a whole fish en papillote before. My visual of a whole salmon wrapped in foil is rather massive and would be hard to handle. For my purposes, I decided to scale the recipe down.
Salmon filets are a great substitute for sea trout. I also believe arctic char or small rainbow trout would work too. Perhaps, I may have to go to the UK to get sea spinach, but now and then sea trout is available in our stores in the Northeast US. I substituted baby spinach to replace the sea spinach. It may not have the ocean saltiness, but the baby spinach has a wonderful smoothness and flavor in a butter sauce.
The spinach butter sauce is an adaptation of a beurre blanc, a French white butter sauce, and is traditionally served with fish. It is not difficult to make, but you must be patient and not let the butter get too hot. While I am whisking in the butter, I usually move the pan on and off the heat to control the temperature. It is important to keep whisking away until the butter is all incorporated. Your whisking, and keeping the temperature low, are the keys to get the butter emulsified in the sauce.
Baked salmon with spinach butter sauce is a delicate and rich dish. Because the spinach sauce must stay warm, and is not easily reheated, it is not a meal that can easily be made ahead. It is possible to cook the fish ahead and serve at room temperature. However, the spinach butter sauce must be warm. I have read that a thermos will help keep the butter sauce warm, or placed in a double boiler on very low heat. Ultimately, it is best to eat salmon with spinach butter sauce as soon as it is done.
This is an elegant meal, and I believe a treat to be served on occasion. Serve along with baby potatoes boiled in salted water then drizzled with olive oil and herbs. You need the boiled potatoes because whatever amount of sauce the salmon does not soak up, the potatoes will. You should not serve this meal with anything else that is rich and fancy. The spinach butter sauce is all the embellishment you need.
A delicious dinner of oven poached salmon with spinach butter sauce, boiled baby potatoes with parsley and chives, green salad with a light dressing, white wine, and good company. Your special dinner is ready.
Oven Poached Salmon with Spinach Butter Sauce
- 5 oz / 150g baby spinach
- 2 lbs / 1 kilo salmon filet or one side of arctic char
- Kosher Salt
- 4 tarragon sprigs divided
- Fennel Fronds optional
- ¼ cup/ 60 ml dry vermouth or dry white wine optional
- 5 Tbs butter plus 1 Tbs
- 1/2 cup / 125 ml heavy cream
- 1 lb / 455 g fingerling potatoes
- 1 – 2 Tbs Extra virgin olive oil
- About 1 Tbs minced chives
- About 2 Tbs chopped parsley
Preheat the oven to 375˚F / 190˚ C / Gas Mark 5
Wash and remove the stems from the spinach. Blanch the spinach in salted boiling water for one minute after the pot returns to a boil. Drain the spinach then shock in ice water. Place the blanched spinach on a clean flour sack towel, or thin kitchen towel, to dry, then squeeze out all the water from the spinach. Finely mince the spinach and set aside.
Cut a piece of aluminum foil that is at least 6-8 inches (20 cm) longer in length, and wider, than your piece of fish. Lay the aluminum foil on a sheet pan, large enough to hold your piece of fish, and smear half a tablespoon of butter across the center part of the foil. Place the salmon on the buttered surface and smear, or dot, the surface of the salmon with a half tablespoon of butter. (If your piece of fish is larger or your a cooking a whole fish, you will need more butter). Sprinkle the salmon with salt and scatter half of the tarragon leaves over the salmon and some fennel fronds. (If you are cooking a whole fish, add the herbs and salt in the cavity of the fish). Add the vermouth or wine if using.
Cover with another piece of aluminum foil and fold in and crimp the 4 sides of the foil to create a tight seal.
Place the fish in the preheated oven and bake for 20-30 minutes, depending on the size and thickness of your fish. Start checking to see if your fish is done at 20 minutes. Press down on the top of the salmon at it thickest part. If it feels tender but firm with some give, then the salmon is done. Once the salmon is done cooking, take it out of the oven and let it rest in the foil for 10 minutes. You can take the salmon out of the oven slightly before it is done, as it will continue to cook while it rests.
In the meantime, mince the remaining tarragon and set aside.
Boil some salted water in a saucepan large enough to hold all your potatoes. Add the fingerling potatoes, whole, to the salted boiling water and cook until done. Depending on the size of the potatoes, they could be done between 10 and 20 minutes. The potatoes are done when you pierce them with a knife, and the knife slides easily in and out of a potato without resistance. Check several potatoes to determine if they are all cooked. Drain the potatoes, and when cool enough to handle but still hot, cut the potatoes in half lengthwise. Lightly drizzle with olive oil, chopped parsley and minced chives.
While the salmon and the potatoes are cooking, make the spinach sauce. Add the heavy cream to a wide mouth saucepan and turn the heat to medium-high. Carefully bring the cream to a boil. Once the cream starts to boil turn the heat slightly down, simmer until the cram is reduced by half its volume, ¼ cup. Once reduced, add the minced spinach and remaining tarragon and stir to combine. Reduce the heat to low then add the butter, one tablespoon at a time, to the sauce and whisk in completely. Once the butter is thoroughly whisked in, add another knob of butter then whisk and repeat whisking it in. Repeat until all the butter is emulsified in the sauce. While you are making the sauce, watch the heat carefully and whisk constantly, you do not want the butter to get too hot or it will separate or brown. Once the fish is rested, carefully pour out some of the juices from the fish into the sauce, then whisk until combined.
Place the fish on a platter and spoon the spinach butter sauce over the fish. Put any leftover sauce in a bowl for your guests to help themselves. Serve with the boiled potatoes.
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