King Salmon with Pinot Noir Sauce

Ingredients

4 king salmon portions
2 Tbsp plus 4 tsp vegetable oil, divided
3 oz coarsely chopped fresh wild mushrooms
2 large shallots, chopped
1 cup pinot noir wine
4 tarragon sprigs, divided, plus fresh tarragon leaves, for garnish
4 thyme sprigs, divided
4 fennel frond sprigs, divided, plus chopped fennel fronds, for garnish
1 cup fish stock or bottled clam juice
½ cup heavy cream
1 cup unsalted butter (8 ounces), cut into 1/2-inch pieces, divided
2 tsp fresh lemon juice
1 ¾ tsp kosher salt, divided
¾ tsp black pepper, divided

Directions

1. Preheat oven to 400°F. Heat 4 tsp oil in a medium saucepan over medium-high. Add mushrooms and shallots; cook, stirring often, until shallots are softened, about 3 minutes. Stir in wine, 2 tarragon sprigs, 2 thyme sprigs, and 2 fennel sprigs. Return mixture to a simmer over medium-high, and cook until wine is reduced by half, 4-5 minutes. Stir in stock and cream, and return to a simmer. Cook, stirring occasionally, until reduced, about 18-22 minutes.
2. Remove sauce from heat, and gradually whisk in ½ cup butter. (You may need to return saucepan to heat briefly to melt butter; do not let mixture come to a simmer or sauce will break.) Pour sauce through a fine wire-mesh strainer into a small heatproof bowl; discard solids. Stir in lemon juice, ½ teaspoon salt, and ¼ teaspoon pepper; cover to keep warm.
3. Season tops of salmon portions with remaining 1 ¼ teaspoons salt and remaining ½ teaspoon pepper. Heat 1 Tbsp oil in a large nonstick or cast-iron skillet over medium-high. Add salmon portions, flesh sides down, and sear until lightly browned, about 1 minute. Flip portions, and sear until skin is lightly browned, about 1 minute. Transfer cooked portions, skin sides down, to an aluminum foil–lined rimmed baking sheet, spacing fillets ½ inch apart.
4. Top portions with remaining ½ cup cubed butter, remaining tarragon sprigs, thyme sprigs, and fennel sprigs. Bake in preheated oven to desired degree of doneness, 6-8 minutes for medium.
5. Spoon about 2 Tbsp warm wine sauce onto each of 10 dinner plates. Using a spatula, carefully slide salmon portions off their skins, leaving skins and herb sprigs on baking sheet. Pat bottoms of cooked fish with paper towels. Place fillets on sauce, skinned sides down. Garnish with tarragon leaves and fennel fronds, and serve immediately.