Peel the carrot, celery and leek and cut into fine strips.
Preheat the oven to 220°C (200°C fan, gas 7). Prepare all the ingredients.
Pat dry the fish fillet.
Spread out the vegetables in a shallow baking dish.
Add the wine.
Dot with the butter.
Cut the fish fillet into 4 equal pieces.
Place on the vegetable bed.
Season with salt and pepper.
Cover with foil. Cook in the oven for 15-20 minutes.
Remove from the oven and remove the foil.
Season the vegetables and serve with the fish on plates. Top with lemon slices.
Spoon the sauce around the fish. Serve with chips and asparagus if desired.