Take a bowl, mix refine flour, ajwain seed, 1/4 portion of oil and salt.
Add enough water and prepare soft dough. Cover and leave it for 30 minutes.
After 30 minutes, take small portion of dough and roll them with the help of some dry flour in your hands. Press the dough ball to form large thin rounds. Prick all over with fork. Cut out small circles to form papdi of it with cutter.
Take a pan & heat oil in it. Fry the small papdis until they turn golden brown in color.
Place the fired Papadis in a large plate.
Add chopped potatoes, onions, tomatoes and green chilies over it. Spread the beaten curd all over the papdis and vegetable.
Now, sprinkle chutneys, salt, red chili powder, black salt cumin and Chaat masala all over.
Garnish your Chaat with chopped green coriander, shredded ginger and sev. Ta-Da! Your Aloo Papadi Chaat is ready!