Method

• Begin by making the pastry - whiz flour and salt in a food processor
• Drizzle in oil and then water
• Process for about 1 minute until mixture forms a ball
• Transfer to a floured work surface and knead for 2-3 minutes until supple and smooth
• Put into a bowl, cover with a clean cloth and refrigerate for at least 1 hour
• Add the butter and oil to a medium fry pan and add the leeks and tarragon (if using) and cook gently without colouring for 5 minutes, season lightly with salt and cracked pepper
• Cool, set aside
• Mix the crème fraiche with the mustard and set aside
• Preheat the oven to 200C To Assemble: Divide the pastry into two and roll one round of pastry about 25cm diameter (size of large dinner plate)
• Roll second half so that it is a little larger in size about 20cm diameter (this is the top)
• Lightly oil a large baking sheet and place the smaller of the two rounds on the tray
• Spread the crème fraiche mixture over the base allowing 2 cm from the edge
• Scatter over the cooked leeks
• Place the sliced ham over the leeks and finally add the gruyere cheese
• Place the second round over the pie and allow the pastry to fall over the mixture
• Seal edges, then fold extra pastry from base to over sealed edges and press together
• Pierce top here and there with a fork and drizzle with 1 tablespoon oil
• Scatter with the sea salt and bake in preheat oven for 30-40 mins or until golden and pastry is cooked
• Remove from oven and cool for at least 10 minutes before cutting
• Enjoy!