Instructions

1. Peel then cut the potatoes into 2-3cm cubes. Put them in a pan of cold water, bring to the boil, then drain.
2. Meanwhile peel and cut the sweet potatoes into cubes of similar size and fry these in the oil for 5 minutes. Transfer them to a mixing bowl.
3. Chop the onion, garlic, chilli and add the oil with the ground ginger. Stir for a minute them put back the sweet potatoes. Add the potatoes, lentils, garam masala, and pour the stock over.
4. Bring to the boil, then cook gently under cover for 20-25 minutes until the vegetables are tender. If necessary, add more water.
5. Serve hot.