Spray a large frying pan with low-calorie cooking spray and place over a medium heat. Add the chicken and fry for 8-10 minutes, or until golden and cooked through. There should be no signs of pinkness inside and the juices should run clear. Remove from the frying pan and set aside.
Add the onion, chilli, garlic paste and ginger paste to the frying pan. Stir and fry over a medium heat for about 5 minutes, until the onion is translucent but not browned.
Add the cooked chicken, garam masala, chaat masala seasoning powder and tomato puree, stir, and cook for 5 minutes.
Remove from the heat and stir in the cucumber, tomatoes and coriander leaves. Taste and season well with salt and black pepper.
Place on small plates and add a lemon wedge to each. Squeeze the lemon wedges over just before eating. Serve with rice and a dollop of natural yoghurt or raita (optional) or other accompaniments of your choice.