Method

• 1.
  For the pastry, sift flour into a large bowl. Add 1 tsp salt, then make a well in the centre. Add the butter, water and beaten egg to the centre then gently bring the mixture together to form a dough. Knead until smooth then wrap in cling film and rest in the fridge for 30 minutes.

• 2.
  Meanwhile, heat half the oil and butter in a frypan over medium-high heat. Add half the mushrooms, season and cook 4-5 minutes until golden. Remove from pan. Repeat with remaining oil, butter and mushrooms. Add remaining ingredients to the mushrooms, combine and cool.
• 3.
  Preheat oven to 180C. Grease a baking tray and line with baking paper.
• 4.
  Generously flour your work surface and roll the pastry into a rectangle 2-3mm thick – it should be almost see-through. Place the pastry on a large piece of baking paper. Spread mushroom mixture lengthways down one long side of the pastry, about 4cm in and leaving 4cm at each end. Fold in the ends, then carefully roll into a sausage shape.
• 5.
  Place strudel seam-side down on a lined baking sheet. Brush the top with egg wash. Bake for 40 minutes or until golden.
• 6.
  Remove from oven and rest for 10 minutes for the filling to firm up before slicing.