Rinse 3 cups sabudana thoroughly, then soak it in enough water to just cover the pearls for 4 to 6 hours or overnight.

Drain the soaked sabudana completely and spread it briefly so the pearls are dry rather than wet.

Mash 2 boiled potatoes until smooth, then chop the remaining boiled potato into small cubes for the filling.

Combine the drained sabudana, mashed potato, 1/2 cup buckwheat flour, crushed peanuts, cumin seeds, ground cumin, ground coriander, red chilly powder, 1 teaspoon salt, and 1 teaspoon black pepper.

Knead the mixture into a firm, cohesive dough, adding 1 to 2 teaspoons water only if it feels too dry.

Divide the dough into 4 equal portions, then press each portion into a small bowl-shaped basket with a thick base and raised sides.

Heat neutral frying oil in a deep frying pan over medium heat until a small piece of dough sizzles immediately.

Fry the sabudana baskets in batches until golden and crisp, turning carefully so they retain their basket shape.

Lift the fried baskets with a slotted spoon and drain them on paper towels for 2 minutes.

Fry the chopped boiled potato cubes until lightly crisp, then season them with the remaining salt and black pepper.

Whisk plain yogurt with sugar until smooth, then chill it until ready to assemble.

Place one crispy sabudana basket on each serving plate and fill each basket with an equal amount of fried potato.

Spoon sweetened yogurt over the potato filling, then drizzle each basket with tamarind chutney and green chutney.

Top the chaat with pomegranate arils and fresh coriander, then serve immediately while the baskets remain crisp.