1.Cook onion and oil in a heavy-based saucepan on medium heat for 10 minutes, until starting to colour. Add garlic and cook, stirring, for 1-2 minutes, until onion and garlic are golden.
2.Add curry powder and mustard seeds, and cook, stirring, for 3 minutes. Add potatoes, chickpeas and enough water to just cover all ingredients. Bring to a simmer. Add chilli and ginger and a little salt, and simmer for 15 minutes.
3.Stir through tomatoes, half of coriander and lemon juice. Simmer for 10 minutes, until vegetables are tender. Stir in remaining coriander. Top with extra coriander and serve with rice and pappadums, if desired.
The yellow flesh and waxy texture of nadine potatoes make them great for stews, for dishes requiring a strong potato flavour and for dishes where potatoes need to remain firm and whole, such as salads or chunky soups.