Heat the oil in a frying pan over a low heat and cook the peanuts for 5 mins until roasted and golden. Add the mustard seeds and curry leaves and sizzle for a few seconds.

Add the onions, potatoes and 2 tbsp water, then cover and cook for 10 mins until the potatoes are soft. Remove from the heat, add 1/2 tsp salt and 1/4 tsp freshly ground black pepper, and mix well. Leave to cool slightly, about 30 mins.

Transfer to a large bowl and add the remaining ingredients.

Mix the dressing ingredients together in a separate small bowl, pour this over the salad, toss well to coat everything, and serve.