In a large bowl, blend Greek yogurt, lemon juice, ginger-garlic paste, turmeric, garam masala, cumin, coriander, smoked paprika, chili powder, and salt. Cut the chicken into bite-sized pieces and coat them thoroughly in this flavorful marinade. Cover and refrigerate for at least 1 hour—preferably overnight.

Heat a grill pan or skillet over medium-high heat. Add oil, then add the marinated chicken pieces in a single layer. Sear the chicken for 5-7 minutes on each side until cooked through and charred. Transfer the chicken to a plate and let it rest.

In the same pan, add butter or ghee over medium heat. Once melted, add the chopped onion and sauté for about 5-6 minutes until golden brown. Stir in minced garlic and ginger, cooking for an additional minute.

Sprinkle in turmeric, garam masala, cumin, coriander, and chili powder. Stir continuously for a minute to release their flavors. Add the tomato paste and crushed tomatoes, mixing well. Allow to simmer gently for about 10 minutes until thickened.

Reduce heat to low and pour in the cream or coconut milk, stirring until combined. Simmer for 5 minutes to meld flavors. Adjust seasoning with salt or a pinch of sugar.

Add the cooked chicken into the simmering sauce, gently folding it in. Simmer for an additional 5 minutes. Finish with a squeeze of lemon juice and chopped cilantro before serving.