Jersey Royal chaat

1. Preheat the oven to 200ºC, gas mark 6. Put the potatoes in a large pan of cold, salted water and bring to the boil. Cook for 12-15 minutes until just tender, then drain and leave to steam dry in the pan. Transfer to a roasting tin and crush the potatoes lightly with a potato masher or the back of a large spoon so they flatten and break. Drizzle over the vegetable oil and scatter with the cumin seeds; season. Roast for 45-50 minutes, until golden and crisping up around the broken edges. 

2. When the potatoes have 10 minutes to go, put the yogurt in a bowl and mix with the chaat masala, lemon juice and ½ the coriander. Taste and add a little more chaat masala, if you like. Spoon over a serving platter. In a small bowl, mix the sugar with 1 tbsp just-boiled water, then add the tamarind and chilli powder; set aside. When the potatoes are ready, toss the chickpeas through them, then pile on top of the yogurt dressing. Drizzle over the tamarind dressing and top with the Bombay mix, onion and remaining coriander. Serve straight away.