Heat the vegetable oil in a large deep pan or kadai over medium heat. Add the finely chopped onion and cook for 8 to 10 minutes, stirring occasionally, until they turn soft and light golden brown at the edges.

Add the ginger-garlic paste and sauté for 1 minute until the raw smell disappears. Reduce the heat to low. Add the Madras curry powder, Kashmiri chili powder, ground turmeric, ground cumin, and salt. Stir constantly for 30 to 45 seconds to bloom the spices in the warm oil, ensuring they do not burn.

Add the chicken pieces to the pan. Turn the heat up to medium and stir well to coat the chicken entirely with the spice mixture. Cook for 3 to 4 minutes, stirring often, until the chicken pieces are lightly seared and no longer pink on the outside.

Pour in the canned tomato purée, tomato paste, and water. Stir well to combine, scraping up any browned bits stuck to the bottom of the pan. Bring the mixture to a gentle boil, then cover the pan with a lid and reduce the heat to low. Simmer for 12 to 15 minutes, stirring occasionally, until the chicken is tender and cooked through. Ensure the thickest piece of chicken registers an internal temperature of 74°C / 165°F.

Remove the lid and stir in the fresh lemon juice. Let the curry simmer uncovered for another 1 to 2 minutes so the flavors meld and the gravy reaches your preferred thickness. Turn off the heat, garnish with chopped coriander leaves, and serve hot.