Burgers: Place all the ingredients except the flour in a bowl and mix them together with a fork until well combined. Place the flour onto a large plate. Form the mince into 6 round burgers and coat them in the flour. Cover and refrigerate the burgers until ready to cook.
To Cook: Preheat a barbecue to moderate hot or cook them in a grill pan or frying pan with a little oil over a moderate high heat. Coat the burgers in a little oil before cooking them on the barbecue or grill pan. Cook the burgers for 7-8 minutes on each side so that they are brown and cooked through. Remove the burgers from the heat and keep them warm until ready to serve.
To Serve: Place a chapati on each plate and spread a little mango chutney on each one. Place a handful of the lettuce on the chapattis followed by the burgers. Place a few tomato and cucumber slices on top of the burgers. Spoon over a little raiti and serve.