Take mashed potatoes in a bowl.
Heat one tablespoon oil in a pan. Add onion and sauté till translucent. Add green chillies and sauté for half a minute. Add this to the potatoes along with mashed chickpeas, coriander leaves, salt and mix well. Add lemon juice and mix.
Take a portion of this mixture and shape into a ball. Roll in breadcrumbs and shape into a patty. Similarly make more patties with the rest of the mixture.
Heat a pan, pour a little oil and place the patties, a few at a time, and cook till evenly golden on both the sides.Slit burger buns and place them on the hot pan and cook till slightly crisp.
Take some lettuce leaves and tear. Apply a little mustard sauce and tomato ketchup on the bottom half of a burger bun and place lettuce leaves over the sauces. Place a patty on the lettuce leaves.
Apply a little mustard sauce and tomato ketchup to the top half of the bun and place some onion rings over the sauces.
Similarly prepare the other burgers and serve immediately.