Season trout fillets with salt, pepper, and lemon juice. Let stand at room temperature for 10 to 15 minutes. Combine 2 Tbsp. of bread crumbs with pecans in blender or food processor. Grind pecans finely, combine with remaining bread crumbs and rosemary, and transfer to plate. Dredge fillets in flour; shake off excess. Dip in egg wash. Place fillets skin-side up on crumb mixture, pressing into flesh. In large skillet heat 1 Tbsp. each of oil and butter over medium-high heat. Place 2 fillets skin-side up in skillet and cook until golden brown, about 3 minutes. Using spatula, turn fillets and cook until opaque in center, about 3 more minutes. Transfer to plate. Repeat with remaining butter, oil, and fillets. Yields 4 main dish servings.