With no-added sugar, the purple fruits in this luscious filling, redolent with cinnamon and vanilla, contain anthocyanins - potent antioxidants, that can reduce inflammation and joint pain - and help protect against heart disease, cancer and dementia. 

The filling must be cool or at room temperature before using, so make it at least an hour and up to 2 days ahead. The strudel itself can be assembled and frozen up to 2 weeks ahead then baked from frozen up to an hour before serving. Taioca flour produces a glossy, jam-like consistency, but cornflour can be used if it's not available. Be sure to use light olive oil spreay which has little or no flavour, not extra virgin. 

• For the filling: Drain the cherries in a colander over a bowl. Put 1 tbsp of the juice in a bowl, add the tapioca or cornflour and mix vigorously to a smooth cream. (Use the spare juice in smoothies and fruit salads.)
• Put the remaining filling ingredients in small saucepan and heat gently until steaming. Stir in the tapioca cream and bring to the boil, stirring gently until it thickens. Remove from heat and cool until needed.
• To assemble and bake: Heat oven to 200°C. Line a rimmed baking tray with baking parchment. Lay a large piece of baking parchment on a clean dry tea towel. 
• Take 6 sheets of filo pastry and cover them with cling film or a clean, dry tea towel to prevent them drying out.
• Working quickly, lay the first sheet of filo on the second piece of baking parchment. Starting at the edges (most prone to drying out) spritz the whole sheet evenly with the olive oil then carefully lay the second sheet of pastry directly on top of the first one and smooth gently. Repeat until you have 6 layers of pastry.
• Spread the filling in a 5-cm band about 7.5 cm from the edge of the pastry nearest to you, leaving 2.5 cm of pastry clear of fruit at either side. 
• Turn the sides of the pastry in to seal in the juices and using the paper and tea-towel, roll into a strudel. Spritz the top and sides with an even layer of olive oil then transfer to the lined baking tray, seam down. Make 6-8 diagonal slashes through the top layer of pastry to make it easier to slice once baked.
• Bake for 25-30 minutes, until crisp and golden brown and serve within two hours, warm, on its own or with creme fraiche, Greek yoghurt, smetana or vanilla ice cream.
• If making ahead freeze the filled, uncooked strudel on a baking tray for 30 minutes until very firm, then wrap tightly with cling film then foil and freeze for up to 2 weeks. Bake from frozen at 190°C for 35-45 minutes until the pastry is crisp and a rich golden brown.