Mix the flour, water, coriander, and salt in a bowl to form a dough.
Cover the dough and chill in the fridge for 20 minutes.
Dry fry the peppercorns, coriander seeds, cumin seeds, and cardamom seeds until fragrant.
Grind the toasted seeds with the remaining spices into a fine powder.
Sauté the onion, garlic, chilli, and ginger in oil for 12 minutes until caramelized.
Add all the tomatoes and spice mix, then bring the mixture to a boil.
Stir in the lentils and simmer for 20 minutes until soft.
Add the blanched potatoes and cook for a further 10 minutes.
Stir in the chickpeas, lime juice, and fresh coriander to warm through.
Roll the dough into 5cm discs after dividing it into small balls.
Deep-fry each puri for 1 minute until puffed and golden, then drain on paper.
Serve the curry alongside the puris with a smear of Greek yoghurt.