Pat fish dry, and sprinkle both sides with black pepper and pinch of salt. Sprinkle with flour.
Melt 1 tablespoon of butter in a large nonstick skillet over medium heat.
Add fish to pan and cook 5 minutes or until lightly browned.
Carefully turn fish over; cook 4 minutes or until fish flakes easily when tested with a fork or until desired degree of doneness.
Remove fish from pan; set aside cover with foil and keep warm while you make the pan sauce.
Add remaining 1 tablespoon butter to pan, and cook 1 minute or until lightly browned, swirling pan to melt butter evenly and prevent burning.
Remove pan from heat; stir in juice.
Drizzle juice mixture over fish.
Sprinkle with parsley.
Serve immediately with additional lemon if desired.