In a bowl, mix yogurt, lemon juice, salt, cumin powder, turmeric, and half the minced garlic.
Add the chicken pieces and coat well. Marinate for at least 10 minutes (or up to 1 hour in fridge).
Heat oil in a heavy pan over medium heat. When hot, add cumin seeds; as they crackle, stir in the remaining garlic and sliced onions.
Sauté until the onions soften and begin to colour, about 3 minutes.
Add the marinated chicken and stir-fry on high heat for 4–5 minutes until the edges start to brown.
Add the green chillies and black pepper, stir well. Pour in water, reduce heat to medium, cover and cook for 8 minutes, stirring occasionally.
Remove lid and increase heat slightly. Cook, stirring, until excess moisture evaporates and the chicken develops a slight crust, about 2 minutes.
Stir through fresh coriander leaves, adjust seasoning if needed, and serve immediately.
