Combine lemon juice, oil and mustard in a jar. Shake well. Brush both sides of the fish with the mixture.
Combine nuts and basil on a large plate. Coat both sides of the fish fillets.
Place fish in a single layer on an oiled baking dish. Cook for 10 - 15 minutes at 190°C. Serve with steamed vegetables and oven-cooked jacket potatoes, if desired.