Place the potatoes and carrot in a small saucepan of cold water, bring to the boil then lower the heat and cook for 6 minutes or until soft. Drain well.
While the potato and carrot are cooking, spray a frying pan with low-calorie cooking spray and set on a medium heat. Fry the onion, garlic and ginger for 5 minutes.
Add the garam masala, turmeric, cumin, coriander and chilli powder and give the pan a stir, coating the vegetables in the spices. Add the boiling water and tomato puree and lower the heat.
Add in the potatoes, carrots and peas and give everything a good stir, season to taste with salt and pepper. Remove the pan from the heat and leave to cool slightly.
Preheat the oven to 180°C and line a baking tray with non-stick baking paper.
Unroll the pastry sheet, leaving it on the greaseproof paper packaging, and place on your work surface. Once the filling has cooled, spread it over the pastry evenly leaving a 1cm gap on the two long edges.
Roll up the pastry starting with the long edge closest to you, using the greaseproof paper packaging to help you. Keep rolling until you have made a ‘Swiss roll’. When you have finished rolling the pastry up, make sure it is seam-side down.
Use a large, serrated knife to cut into 16 spiral-shaped slices. Place the swirls flat onto the lined baking tray, leaving gaps between each swirl.
Place the tray into the oven for 20-25 minutes, until golden and crisp. Place on a cooling rack to cool or serve warm fresh from the oven.