Heat the vegetable oil in a large pan over medium heat.

Add the chopped onions and cook until softened and translucent, about 5 minutes.

Stir in the minced garlic, grated ginger, and chopped green chillies, and cook for another 2 minutes.

Add the chicken pieces to the pan and cook until they are browned on all sides.

Sprinkle the ground cumin, ground coriander, turmeric, paprika, and garam masala over the chicken, and stir well to coat.

Pour in the chopped tomatoes, water, and tomato puree, and season with salt and pepper to taste.

Bring the mixture to a simmer, then reduce the heat to low and cover the pan.

Allow the balti to cook gently for about 20-25 minutes, stirring occasionally, until the chicken is cooked through and the sauce has thickened.

Once cooked, remove from the heat and stir in the chopped fresh coriander.

Serve the chicken balti hot with basmati rice or naan bread.