Smokey Fish Pie

Ingredients

• 900 g potatoes
• 50 g butter
• 1 tbsp sunflower oil
• 50 g carrots
• 1 stalk celery
• 200 g smoked haddock
• 200 g cod fillets
• 75 g butter
• 75 g flour
• 500 ml milk
• 100 g cheddar cheese
• 1 tbsp Dijon mustard
• salt
• black peppercorn
• 4 heads spring onion
• 1 pinch salt
• 2 cloves garlic
• 50 g cheddar cheese
• 100 g Petit pois
• 50 ml milk