To begin, sift the flour into a large bowl and make a well in the centre. Add the vinegar, salt, oil and half of the water and mix together with a fork until it starts to come together. Add as much of the remaining water as you need to make a dough and turn it out onto a lightly floured work surface

Knead for a few minutes until you have a soft, but not sticky dough. Wrap in cling film and leave to rest for at least 20 minutes

In the meantime, make the filling. In a pan over a medium heat, sweat the onion, leeks, garlic and bacon in a little oil (or butter) until soft and slightly golden. Stir in the feta and parsley and season generously. Transfer to a bowl and leave to cool

Use your hands to roll the dough into a sausage and cut into 10 pieces. Take a piece of dough and cover the remaining 9 pieces with cling film to prevent them from drying out

Roll the dough as thinly as you possibly can into a large rectangular shape, then gently stretch it further using your hands. Ideally the dough should be thin enough to be able to see your hand through it

Once the dough is as thin as you can make it, brush the filo sheet with melted butter/oil and cover with cling film. Roll out the next piece in the same way, remove the cling film from the first sheet and place the second over the top

Brush liberally with more melted butter and place the sheet of cling film back on. Continue until all the dough has been rolled and brushed with melted butter, giving you 10 layers

Preheat the oven to 220°C/gas mark 7

Place the layered filo in front of you, horizontally, and trim off the edges of the pastry to make a neat rectangle. Spoon the filling into a line a few inches in from the edge of the filo closest to you. Now for the fun bit!

Roll the whole thing up tightly into a long sausage and, with the seam underneath, coil the sausage into a tight ring. Butter a round ovenproof dish, big enough for the pie to snugly fit into the dish. Use a couple of fish slices, or any other long flat implement to hand, to carefully transfer the pie to the dish

Brush the top of the pie with more melted butter and sprinkle over a little salt and pepper. Place the pie in the oven and bake for 20 minutes

Reduce the oven temperature to 180°C and continue to bake for another 20 minutes. Leave to cool for 15–20 minutes before carefully transferring the pie to a serving plate. Slice into wedges to serve