Boil the potatoes until soft. This should take around 4 minutes.
In a separate pan, boil the chickpeas at the same time as the potatoes. This should also take around 4 minutes.
Whilst the potatoes and chickpeas are boiling, add the yoghurt, tomatoes, red onion, red chilli powder, salt, cumin, chaat masala, caster sugar, lemon juice, tamarind sauce and fresh coriander to a serving dish. Mix through thoroughly.
Once the chickpeas and potatoes are soft, drain and leave to cool slightly. Once they have sat for a couple of minutes, add both to the serving tray and mix through.
Finish with dollops of natural yoghurt, and drizzle the tamarind sauce across the yoghurt. Sprinkle some more chaat masala and pomegranate on top. You can store the mixture in the fridge until you want to serve.
When you are due to serve, sprinkle over the fresh coriander and finish with either papri or sev and leave extra for your guests to take. Do not add the papri or sev too early as it will become soft and soggy, you want to keep the crunch of the chaat.