Ingredients
1/4 cup extra-virgin olive oil, plus more for baking sheet
1/4 cup (1/2 stick) plus 1 tablespoon unsalted butter
8 ounces small matsutake mushrooms, peeled and cut into quarters, plus 1 whole, peeled and thinly sliced
Coarse salt and freshly ground white pepper
Espelette pepper
1/2 cup plus 2 tablespoons sake, preferably Junmai Dai Ginjo
1 cup homemade or store-bought low-sodium chicken stock
1/8 teaspoon freshly squeezed lemon juice
3 sprigs fresh rosemary, plus 1 tablespoon chopped
4 (5-ounce) black sea bass fillets
1 small bunch chives, chopped
Preparation
Heat 1 tablespoon olive oil and 1 tablespoon butter in a medium high-sided skillet over medium-high heat. Add 8 ounces mushrooms and cook, stirring, until lightly browned, 1 to 2 minutes. Season with salt and espelette pepper. Add sake to deglaze, scraping up any browned bits from bottom of skillet; cook until sake is reduced by half.
Add chicken stock and 1/8 teaspoon lemon juice; season with salt and espelette pepper. Add rosemary sprigs and let cook until liquid is reduced by half. Using a slotted spoon remove mushrooms and rosemary; set mushrooms aside and discard rosemary.
Gradually add remaining 1/4 cup (1/2 stick) butter and 1 tablespoon olive oil to skillet, using an immersion blender to combine. Add mushrooms and stir to coat. Set mushrooms aside in a warm place.
Preheat broiler; lightly oil a small baking sheet and set aside. Heat remaining 2 tablespoons olive oil in a large nonstick ovenproof pan over high heat. Season on both sides with salt and pepper. Add fish to skillet, skin side down. Cook until skin is crisp, 4 to 5 minutes. Transfer to prepared baking sheet and place under broiler; cook until fish is no longer opaque, about 1 minute more. Remove from broiler and keep warm.
Add chopped rosemary and stir into mushroom mixture along with chives; divide mushroom mixture evenly among 4 plates. Top each with a fish fillet and thinly sliced mushrooms; season with salt and pepper. Spoon any remaining sauce from mushroom mixture around fish; serve immediately.