Method
Preheat the oven to 220ºC (210ºC if fan oven).
Chop the small leek and grate the potato coarsely. Peel and crush garlic. Grate lemon zest finely.
Melt the butter in saucepan and add drop of olive oil. Gently sauté the leeks, grated potato, garlic and lemon zest until softened.
Add a squeeze of lemon juice and 2–3 tablespoons of crème fraîche. Finally add finely cut smoked salmon.
Cut pastry into four squares. Place a reasonable amount of the smoked salmon mixture into the centre of each square. Sprinkle the grated mature cheddar on top.
Brush beaten egg along the four edges. Bring together the four corners and pinch together in the middle of the square shape. Brush any outside pastry with beaten egg mixture.
Place in oven until pastry is well cooked and golden brown.
Serve with rocket salsa salad.