Mix the onion, cucumber, tomatoes, coriander greens, chili peppers and lemon juice in a bowl.
Heat the oil in a frying pan. Add peanuts and salt and fry for a minute. Sprinkle with pepper and chaat masala, stir and fry for one to two minutes (caution - burns easily). Remove from heat and pour over the salad mixture.
Season with salt just before serving so that the ingredients don`t give off too much liquid.