Tarragon Roasted Halibut with Hazelnut Brown Butter

INGREDIENTS

• 1/2 blanched hazelnuts
• 1 large bunch fresh tarragon
• 1 3-3 1/2-pound skinless halibut fillet (halved lengthwise if very wide)
• 4 olive oil, divided
• Kosher salt, freshly ground pepper
• 1/2 (1 stick) unsalted butter
• 1/4 fresh lemon juice
• Lemon halves