Start this recipe the night before if possible. Slice the whole piece of salmon in half horizontally and squeeze over the orange juice. Cover and allow to infuse overnight if possible. When you are ready to prepare the salmon, fry the spring onions in a pan with the oil then add in the chopped spinach and wilt. Remove of the heat and allow to cool before stirring in the cream cheese, orange zest, chopped dill and season with salt and pepper. Roll out the pastry into a large rectangle and brush all over with a little beaten egg. Place over 1 piece of marinated salmon and pile the filling on top. Cover with the remaining piece of salmon and wrap up in the pastry. Seal the edges together firmly place onto a large baking tray. Brush all over again with egg and decorate with pastry leaves and sesame seeds. Use a sharp knife to make a few holes in the top to allow steam to come out during cooking. Bake in the oven at 200c and cook for 30-40 minutes until golden brown. Allow to sit for 5 minutes before cutting into slices and serving with roasted vegetables and potatoes.