Heat 1 tbsp oil in a flat pan and add the thick sliced onion.
Mix and add a pinch of salt. Continue to fry on low heat for around 15 mins to caramelize the onion.
Add the chopped green chillies and mix it well and fry on low heat for a minute.
Now add the shredded boiled chicken and mix it well.
Add the powders & salt, give a mix and add a dollop of butter. Fry on low heat for 2 mins.
Take it out in a bowl and allow it to cool.
Add the mayonnaise and chopped parsley/coriander & mix it well.
To prepare the sandwich, cut off the bread crust. Take 1/4 th of the chicken mix and spread it on one slice. Spread it evenly & in such a way it doesn’t go till the edges. Place the other slice on top & press it.
You can optionally grill it on a grill pan or toast it on a pan with butter till evenly browned or just have it like this.
Cut diagonally into two.
Repeat for the balance 3 sandwiches.