Prepare the topping
7 minFinely dice the yellow onion, tomato, and green pepper, aiming for pieces about the size of a grain of rice. Cut out and discard the watery, seedy center of the tomato; the less liquid in the topping, the longer the wafer stays crisp. Chop the fresh cilantro and add it, then mix in the lemon juice and chaat masala. Set the bowl aside.