Preheat the oven to 190C/375F/gas 5. Mix the sweet potato puree with the peas, sweetcorn and spices. Season to taste with salt & pepper. Lay out 3 sheets of filo pastry on top of each other and slice into thirds lengthways so you get 3 long strips 3 sheets thick. Scoop a heaped tablespoon of the samosa filling onto the bottom of each strip, and brush olive oil on the pastry around it. Fold the corner in over the pastry to form a triangle, then roll over a couple of times to use up the rest of the pastry and keep a triangle shape - alternatively, fold over the bottom corner twice to make a triangle shape first and then fill the pastry (see video here for a great visual walk-through of this way). Brush all over with more olive oil, then place on a lined baking tray. Repeat with the other two strips of pastry, then repeat the whole process twice with the other 6 sheets of filo pastry and the leftover filling. When you have 9 samosas, all folded and brushed with olive oil, bake in the preheated oven for 25-30 minutes, until the pastry is golden and crispy and the filling hot. Serve warm or cold with a sugar free dip like this BBQ sauce and/or salad.