Pour vegetable oil into a large pot over medium heat. Allow it to warm up, then add the finely chopped onions. Sauté until they turn golden brown and caramelly, about 8-10 minutes.

Stir in the minced garlic and grated ginger, letting them sizzle and release their fragrant oils. Cook for 2 minutes, keeping a watchful eye to prevent burning.

Sprinkle in the ground turmeric, ground coriander, ground cumin, garam masala, and cayenne pepper. Stir the mix and cook for 1 minute until the spices bloom.

Toss in the chicken pieces, ensuring each one is well-coated with the spice mixture. Sear them for 2-3 minutes, until they start to brown slightly.

Pour in the pureed tomatoes and season with salt. Cover the pot and let it simmer gently for 10 minutes.

Add the coconut milk and slit green chilies, bringing the mixture to a boil. Once boiling, reduce the heat and simmer for 20-25 minutes.

Taste your curry and adjust the salt and spice levels to fit your preference.

Before serving, sprinkle freshly chopped coriander leaves on top.