Preparation time : 15 minutes
Cooking time: 25-30 minutes

1. Preheat oven to 400°F / 200°C.
2. Season salmon with salt and pepper.
3. In a large skillet, heat oil over medium-high heat. Add mushrooms and onions. Cook until golden, about 4 minutes.
4. Add spinach, remove from heat and let rest until spinach is wilted. Sprinkle with dill and stir in cooked rice.

Assembly

1. Arrange chilled pastry in the centre of a parchment-lined baking sheet.
2. Place half of the rice mixture in the middle third of the pastry.
3. Top with salmon.
4. Cover with remaining rice mixture.
5. Fold one side of pastry over salmon. Fold over remaining side of pastry to enclose salmon.
6. Fold ends of pastry underneath salmon.
7. Cut vents in top of pastry.
8. Brush with egg.
9. Bake in the centre of the oven until pastry is puffed and golden, about 20 minutes. Let cool 10 minutes before slicing.

Sauce

1. Meanwhile, in a medium saucepan, melt butter over medium-high heat.
2. Add shallots and cook until tender and translucid, about 5 minutes.
3. Stir in garlic, salt and pepper and cook one minute. Pour in wine and cook until almost evaporated.
4. Pour in cream, milk and dill. Whisking until combined. Keep warm until ready to serve.
5. Slice salmon pastry in half and top with warm dill sauce.