Heat oil in a pan.
Fry half the sliced onions until slightly browned.
Add chicken and sautee until slightly charred.
Add 1 tsp chaat masala. Stir and remove from heat.
In a fresh pan, heat oil.
Fry the rotis/tortillas, one at a time, with eggs (optional) as shown in the video.
Layer the rotis with chicken, remaining onions, chilies, lime juice and remaining chaat masala. Wrap in parchment paper (optional) and serve hot.