2) In a medium bowl, toss the sliced apples with the lemon juice until the apples are thoroughly coated. Add the raisins, 60g of the sugar and 30g cold cubed butter and toss well. Set aside.
3) Lightly dust the counter or work surface with flour. Lay the sheet of puff pastry on top and dust the rolling pin with additional flour. Gently roll the puff pastry to 0.3cm thickness.
4) Spread the apple and raisin mixture over the bottom half of the puff pastry square leaving about 2.5cm of space along the side edges. Fold the top half of the puff pastry over and pinch to seal the edges together.
5) Brush the entire strudel with the melted butter and then sprinkle with cinnamon and the remaining sugar. Using a serrated knife, make 3 diagonal slits across the top of the strudel.
6) Place the strudel on a greaseproof paper lined baking sheet and bake for 40 minutes, rotating halfway through cooking, until the pastry is puffed and golden brown.