1/2 cup hazelnuts 4 (6-ounces) pieces hake fillet 2 tbsp evoo 2 tbsp unsalted butter 1 garlic clove, finely chopped 2 tbsp red-wine vinegar 2 tbsp water 2 tbsp drained bottled small (nonpareil) capers 1/4 cup chopped flat-leaf parsley
Pulse hazelnuts in food processor until finely chopped.
Pat fish dry and season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Heat oil in a large heavy skillet over medium-high heat until it shimmers. Saute fish, turning once, until golden and just cooked through, about 8 minutes total. Transfer to a platter.
Melt butter in skillet, then sauté hazelnuts with garlic until nuts are golden brown, 1 to 2 minutes. Add vinegar and water, scraping up any brown bits, then remove from heat and stir in capers and parsley. Season with salt and pepper, then spoon over fish.