Crumble butter in cubes with flour.
Add salt and egg and knead to a dough. If needed add some water.
Roll out on a floured surface and put in a tart or quiche form. Cut the edges.
Place in fridge.
Cut leek in fine rings. Roast leek in the pan with some oil. Season with salt and pepper. Leave to cool a bit.
Slice smoked salmon in stripes.
Stir creme fraiche, eggs, wild garlic paste, salt and pepper.
Spread roasted leek evenly on shortcrust.
Spread salmon stripes.
Pour gush on it.
Bake in preheated oven at 180°C for about 35 minutes.
Can be served warm or cold.