This is a classic dish from Bentley's Oyster Bar. For chef Richard Corrigan, it brings back great memories of going down to Woodcock Smokery in West Cork, Ireland. Beautiful fish, simply cooked.

Serves 4
Takes 50 mins

INGREDIENTS

• 1kg fish fillets, including salmon, smoked haddock and white fish such as pollack and haddock (keep the smoked haddock trimmings for the sauce)
• 1.5kg floury potatoes
• 2 egg yolks
• 100g butter, plus a little extra for sweating the vegetables
• 1 onion, diced
• 2 garlic cloves, crushed
• sprig of thyme
• 150ml white wine
• smoked haddock trimmings (see above)
• 2 pints milk
• 100g plain flour
• 1 tbsp English mustard
• handful of chives, chopped
• handful of parsley, chopped

To finish

• A squeeze of lemon juice (1 wedge) 
• a handful of fresh breadcrumbs
• A sprinkle of grated parmesan 

METHOD

1. Remove the skin from the fish and cut into bite-sized pieces, reserving the skin of the smoked haddock for the sauce.
2. Heat a little butter in a saucepan to make the sauce. Add the onion, garlic and thyme and sweat until softened. Next, add the white wine and the smoked haddock trimmings and cook for a few mins to burn off the alcohol. Add the milk and bring to just under the boil, then take the pan from the heat and pass the contents through a sieve into a bowl. Keep hot.
3. Melt the 100g butter in a heavy saucepan, add the flour and cook over a low heat, stirring for 5 mins. Pour the hot infused milk into the pan and whisk vigorously until the mixture is smooth and thick. Taste to make sure you can’t taste the flour — if you can, then let it cook gently for a little longer.
4. Whisk in the mustard and add the chives and parsley. Check the seasoning and add salt and pepper and more mustard, if you wish. Leave to cool down while you make the mash — it’s best not to assemble the pie with hot sauce as it will cook the fish too quickly.
5. Preheat the oven to 180°C/ fan 160°C /Gas 4.
6. Peel the potatoes and cook in boiling salted water until tender. Drain in a colander and allow the potatoes to steam for a couple of mins to rid them of excess moisture, then mash and season with salt and pepper. Add the egg yolks.
7. Scoop the mash into a piping bag — it needs to be hot in order to pipe easily.
8. To assemble, spoon a little of the sauce into the bottom of a pie dish. Arrange a selection of fish on top of the sauce. Season with salt and pepper and a squeeze of lemon juice.
9. Completely cover the fish with the sauce, then pipe or spoon on the mash. Mix together the breadcrumbs and parmesan and sprinkle over the top.
10. Place the pie dish on a baking sheet and cook for around 20 mins until the top is golden brown. Serve immediately.