Salmon en croûte with watercress

1. To prepare the watercress filling, heat the olive oil in a large frying pan, then add the shallots. Sauté over a low heat for 8-10 minutes, until softened. Add the garlic and cook for a few minutes more.

2. Finely chop the watercress and capers, then add to the pan and fry for 1 minute more, until slightly wilted. Remove from the heat, tip into a bowl and allow to cool for at least 15 minutes.

3. Meanwhile, season the salmon fillets with salt. Divide the puff pastry into two pieces, one slightly bigger than the other. Roll out the smaller piece into a rectangle slightly larger than the pieces of fish. Place one salmon fillet into the centre of the pastry, skin-side down.

4. Stir the crème fraîche and lemon zest into the watercress mixture and season with black pepper. Spread the filling over the top of the salmon, then sandwich with the other fillet, skin-side upwards to create a block.

5. Use a pastry brush to coat the exposed pastry around the salmon with beaten egg. Roll out the remaining pastry into a thin rectangle large enough to cover all the filling with a little overhang, then drape over the salmon. Press firmly to create a seal around the edge. Trim to neaten if necessary, then transfer onto a small baking tray, cover and chill in the fridge for 30 minutes.

6. Meanwhile, preheat the oven to 220°C, gas mark 7, and if you’ve got one, place a baking sheet or pizza stone into the oven to heat up (this will ensure a crisp base). Brush the chilled salmon en croûte liberally with beaten egg, then score a zigzag pattern into the top with a sharp knife.

7. Bake (placing the tray onto the preheated baking sheet, if using) for 20 minutes, then reduce the temperature to 200°C, gas mark 6 and bake for a further 30 minutes. The pastry should be golden and crisp all over. Allow to stand for a few minutes before serving. Delicious with a crunchy side salad.