Coulibiac

1. Cook the Rice:
- Cook the rice according to the package instructions until tender. Drain any excess water and set aside to cool.

2. Prepare the Salmon:
- Preheat your oven to 350°F (175°C).
- Place the salmon fillet on a baking sheet and season with salt and pepper.
- Bake the salmon in the preheated oven for about 15-20 minutes, or until it flakes easily with a fork. Remove from the oven and let it cool. Once cooled, flake the salmon into small pieces.

3. Prepare the Filling:
- In a large skillet over medium heat, melt the butter.
- Add the finely chopped onion and sauté until it becomes translucent.
- Add the chopped mushrooms and sauté for an additional 3-4 minutes until they are soft.
- Stir in the cooked rice, flaked salmon, chopped dill, and lemon juice. Mix well to combine. Season with salt and pepper to taste. Allow the filling to cool slightly.

4. Assemble the Coulibiac:
- Preheat your oven to 375°F (190°C).
- Roll out one sheet of puff pastry on a floured surface to smooth its edges. Transfer it to a baking sheet lined with parchment paper.
- Spread the salmon and rice mixture in the center of the puff pastry, leaving about a 1-inch border around the edges.
- Brush the edges of the puff pastry with the beaten egg.
- Roll out the second sheet of puff pastry and place it over the filling. Press the edges together to seal. You can crimp the edges with a fork or twist them decoratively.
- Brush the top of the pastry with the remaining beaten egg to give it a golden color when baked.
- If desired, cut a few small slits or decorative patterns on the top of the pastry to allow steam to escape.

5. Bake:
- Bake the coulibiac in the preheated oven for about 25-30 minutes, or until the pastry is golden brown and cooked through.

6. Serve:
- Allow the coulibiac to cool for a few minutes before slicing.
- Serve warm, and enjoy your delicious homemade coulibiac!