Heat the oil in a large pan over medium heat.
Add the chopped onions and sauté until they turn translucent and start to brown, about 5-7 minutes.
Add the minced garlic, ginger and green chillies to the pan and cook for another 1-2 minutes until fragrant.
Add the chopped tomatoes to the pan and cook for 4-5 minutes until they become soft and pulpy.
Add the chicken pieces to the pan and stir well to coat them with the tomato mixture and cook for 5-7 minutes, until the chicken changes colour.
Add the ground coriander, ground cumin, turmeric powder, chilli powder, and salt to the pan, and stir well to combine.
Cook for 2-3 minutes, add a 2 tbsp of water, to release the colour of the spices.
Add the water to the pan and stir well. Cover the pan and cook on medium heat for 20-25 minutes, stirring occasionally, until the chicken is fully cooked and the sauce has thickened.
Garnish with chopped coriander leaves and serve hot with rice or naan bread. Enjoy your delicious chicken bhuna!