Bring a large saucepan of water to the boil and add the unpeeled potatoes. Cook for 10–15 minutes until they’re just cooked through and tender to a fork (they’ll take more or less time depending on the size of the potatoes). Drain well, cool in a bowl of cold water and then peel. (You can enlist a partner or small child to help with this bit.)

Meanwhile, heat the oil and butter or ghee in a large frying pan over a medium heat and add the cinnamon scroll, cardamom pods, cloves and bay leaves. Fry for a minute until the bay leaves darken, then add the onions and garlic. Cook over a medium to low heat for 10 minutes, stirring frequently, until the onions soften and just start turning golden brown around the edges.

Add the turmeric, chilli and salt, stir-fry for a further 30 seconds, then add the cooked potatoes and stir gently to coat them in the spiced onions. Add the tomatoes, water and sugar and stir again, then simmer for 10 minutes until the flavours have blended. Taste and add salt as needed, and serve hot.