Clean, wash and cut chicken breasts into finger sized pieces. Peel, halve and cut onions into thick slices.
Separate the different layers of onion. Wash, halve, remove seeds and cut tomatoes and capsicums into long strips of half-centimeter width.
Peel and cut ginger into juliennes. Peel and finely chop garlic. Wash, remove stem and slit green chillies into two. Wash and finely chop fresh coriander leaves.
Heat oil in a non-stick pan and add cumin seeds. When they start to change colour, add mustard seeds and curry leaves. Cook on high heat till mustard seeds start to crackle.
Add chopped garlic and slit green chillies. Stir-fry briefly and add onions. Cook on medium heat for half a minute, stirring frequently.
Add chicken pieces and continue to cook on medium heat for five minutes, stirring occasionally. Add turmeric powder, red chilli powder and salt. Mix well. Add capsicum and ginger juliennes.
Cook on medium heat for two minutes, stirring occasionally. Sprinkle garam masala powder and lemon juice. Mix well and add tomatoes. Reduce heat and continue to cook further for two minutes.
Serve hot, garnished with chopped coriander leaves.