Method

1. Put the rice and stock or water into a saucepan, add the saffron threads and bring to the boil. Reduce heat to very low, cover and steam rice for 12 minutes or until tender.

2. Fluff up rice with a fork and stir in half the chopped dill.

3. Heat a little butter in a heavy-based frying pan and fry the mushrooms until tender.

4. Lay 1 side of the salmon skin-side down.

5. Cover the salmon with a layer of the saffron rice, then the caviar and finally, the mushrooms. Season with sea salt and freshly ground black pepper.

6. Lay the remaining side of salmon over the top, skin-side up, making a kind of sandwich.

7. Preheat the oven to 180C/gas 4 and line a baking tray with baking parchment.

8. Roll out a piece of puff pastry big enough to generously wrap the salmon. Brush the edges of the pastry with the beaten egg and seal the pastry around the salmon. Brush the top of the pastry with remaining beaten egg.

9. Transfer the salmon to prepared baking tray and bake for about 12-15 minutes or until the salmon is cooked.

10. Melt the rest of the butter in a small frying pan, add the lemon juice and remaining dill and whisk together well.

11. Serve the salmon in slices with wilted spinach and the dill butter sauce.