For the pastry

• 400g plain flour
• 200g cold unsalted butter, cubed
• A pinch of salt
• Iced water

For the filling

• 450 to 500g smoked haddock, skinned and pin boned
• 1 tbsp olive oil
• 2 onions, peeled and thinly sliced
• 25g butter
• 20g plain flour
• 150ml whole milk
• 1 tsp English or wholegrain mustard
• 50g mature cheddar, grated
• 1 small bunch parsley leaves, chopped
• 2 tsp fennel seeds
• 1 tbsp finely grated cheddar, for the pastry
• Salt and freshly ground black pepper
• 1 egg
• A dash of milk

To make the pastry, place the flour, butter and salt in a bowl and rub together lightly until the mixture resembles coarse crumbs. Add just enough iced water to bring everything together into a fairly firm dough.

Turn the dough out onto a well floured surface and roll it away from you into a rectangle about 1cm thick. Fold the two short ends into the middle so they overlap. Give the pastry a quarter turn, then roll and fold it again in the same way. Repeat this rolling and folding process five more times. Wrap the pastry and rest it in the fridge for 30 minutes to 1 hour.

Set a large, heavy based pan over a medium heat and add the olive oil. Add the sliced onions, season well with salt and pepper and stir to separate them. Cover with a lid and cook gently for 10 to 12 minutes, stirring occasionally, until the onions are soft and just beginning to colour around the edges.

Add the butter and allow it to melt, then stir in the flour. Cook for 2 to 3 minutes before gradually adding the milk, stirring all the time as the sauce thickens. Add the grated cheddar and mustard, season well and simmer gently for another 2 to 3 minutes. Remove from the heat and leave to cool.

Cut the smoked haddock into 3 to 4cm pieces and fold it through the cooled sauce along with the chopped parsley.

Roll the rested pastry to about 4 to 5mm thick. Using a plate as a guide, cut out four rounds roughly 18 to 20cm in diameter.

Preheat the oven to 180°C fan or 200°C conventional.

Divide the fish filling between the pastry rounds, placing it on the lower half of each circle and leaving a border of about 2cm for sealing.

Whisk the egg with a dash of milk. Brush the exposed pastry edge with the egg wash, then fold the pastry over the filling to form a half moon shape. Press and crimp the edges firmly with your fingers to seal well so the filling does not escape during baking.

Place the pasties on a tray lined with baking parchment. Brush the tops with the egg wash, scatter over the finely grated cheddar and fennel seeds, and finish with a little cracked black pepper.

Bake for 35 to 40 minutes until the pastry is crisp and golden.

Allow the pasties to cool slightly before serving. They are delicious eaten just warm, but equally good at room temperature.