Step 1

Cut the potatoes into bite-sized pieces roughly 3cm square, put these into a medium saucepan, add a teaspoon of salt and cover with plenty of cold water. Bring to a boil, cook until just tender – around eight to 10 minutes – then drain.

Step 2

Meanwhile, pour the oil into a large, deep-sided frying pan for which you have a lid, and put over a medium heat. Add the cumin and mustard seeds to the hot oil and watch carefully: when they start to sizzle, add the diced aubergine, onion and a teaspoon of salt.

Step 3

Turn down the heat a little and cook until the onions and aubergines are soft enough to cut with a wooden spoon and starting to brown – about 10 minutes. Now stir in the ginger and garlic and, after a few more minutes, the turmeric, chilli powder and ground coriander. Mix in the tomato paste, turn the heat to low, cook for a further 10 minutes, then add the drained potatoes and stir gently so as not to crush them.

Step 4

Add a big handful of spinach, stir, add a splash of water and cover with the lid – it will take a few minutes to wilt down. Repeat until all the spinach is wilted and soft. Add a couple of tablespoons of water, mix and cook for two to three minutes more, then take off the heat.

Step 5

Serve with chapatis or naan, yoghurt and a little lime or lemon pickle on the side.