Melt the buter and oil in a large saucepan. Add the onions and cook for 7 minutes until sift a golden. Add the garlic and ginger and cook for an additional minute.
Add the spices including ground cumin, coriander, garam masala, turmeric, smoked paprika and chili powder. Stir for 30 seconds so the spices release their fragrance.
Add the tomato paste and cook for 2 minutes then add in the diced or crushed tomatoes. Allow to simmer for 10 minutes, stirring occasionally.
Reduce the heat and slowly stir in the coconut milk. Continue stirring until fully blended. Stir in the sugar and season with salt and pepper to taste.
Add in the cooked chicken and mix so all the chicken is coated with the sauce. Simmer for an additional 5 minutes. Finish off with a squeeze of lemon and sprinkle of fresh cilantro.
Serve over rice or with naan bread.