Roll out the puff pastry and cut out two large hearts using a heart-shaped tin or a sharp knife.
Combine the crème fraîche, mustard, Siúcra/McKinney's Light Golden Brown Sugar, eggs, leek and dill. Spread the filling onto one of the hearts, leaving a 2 cm margin around the edges.
Arrange the salmon on top of the filling. Brush the edges of the heart with egg wash and place the other heart on top.
Press the edges together firmly to keep the filling from leaking out.
Bake at 200°C for about 25 minutes.
Serve with a fresh salad.