Heat the oil in a large non-stick frying pan. Add the mince and onion and cook for 5-6 mins until brown, breaking up any clumps with a wooden spoon.
Add the carrot, potato, peas, spices and 100ml water. Reduce the heat, cover and simmer for 10 mins until the liquid is reduced by two thirds.
Transfer the mince to a bowl and add the lime juice and the coriander. Set aside to cool
Pre-heat the oven to Gas Mark 6, 200°C, 400°F.
Melt the butter in a small pan. Take half a sheet of filo pastry and brush lightly with the melted butter. Fold in half lengthways. Place a spoonful of the filling at one end, and fold over the corner to enclose the filling. Keep on folding in the shape of a triangle. Tuck the last piece into the last fold, and place, seam side down, on a baking tray lined with greaseproof paper. Bake in the oven for 15 mins until golden brown.
Serve hot with mango chutney, as a snack or as a starter with some salaD
If you have trouble folding them correctly, make some small cornets from a sheet of filo pastry instead, fill up to two-thirds full and fold over the top to close.