Start by making the filo pastry, sieve the plain flour into a bowl. In a separate bowl beat the egg with the water, lemon juice and salt, then mix with the flour
Knead the dough on a floured surface for 10 minutes. Oil your hands to stop it sticking to them
Cover a dining table with an old, but clean, bed sheet or tablecloth. Flour it evenly and well
Roll out the dough as much as you can with a rolling pin, then cover it with a damp tea towel for 15 minutes
Pull and stretch the dough gently with your hands, letting it stretch with its own weight and pulling it as thin as you can
Brush the melted butter all over the dough, sprinkle it with a mixture of the light brown sugar, the zest of the lemon and the cinnamon
Sprinkle the blueberries, raspberries and chopped apples over the pastry. Using the bed sheet to help you, roll up the strudel gently and slowly. Tuck the end in and fold it into a curved 'c' shape
Put it on a lined baking tray and bake it on 160C Fan/180C/350F/Gas Mark 4 for 35 minutes until golden and crisp