Slice the onions and cook over a medium heat in a large pot until golden brown. Stir occasionally.
To the onions, add the garlic and ginger pastes. For 2 minutes stir and then add the salt, chilli powder and turmeric. Fry for another 5 minutes.
To the pan, add the carrots and potatoes. Once almost cooked through, add to the pot the beans, green peas, crushed cumin seeds and cumin powder.
Cook the vegetables over a high heat and remember to stir regularly. The mixture should be quite dry. Remove from the heat and transfer to a plate to cool down.
Preheat the oven to 180°C/350°F/gas mark 4.
Allow the pastry to warm and soften slightly. Unwrap on a chopping board and then cut into two pieces, lengthways.
Spoon the vegetables along one side of the pastry.
Run the edges of the pastry with a dipped-in-water pastry brush and fold over to seal the edges.
Press the pastry gently to form the shape of a sausage roll.
Cut into 1.5 inch long parcels. Place on a baking tray.
Bake for 12-15 minutes or alternatively until the pastry has risen and is golden brown.