Dry roast all masala paste ingredients except tamarind in a pan over medium heat until fragrant and lightly colored.
Grind the roasted spices with tamarind and a little water to form a smooth paste.
In the same pan, roast 1 tsp cumin seeds until aromatic, then grind with grated coconut to make coconut paste.
Heat vegetable oil and ghee in a heavy-bottomed pot over medium heat.
Add chopped onions and curry leaves, sauté until onions turn golden brown.
Add the masala paste and cook, stirring continuously, until oil begins to separate from the mixture.
Mix in the coconut paste and cook for 5 minutes, stirring regularly.
Add chicken pieces, salt, and garam masala, mixing well to coat chicken with the paste.
Cover and simmer for 20-25 minutes until chicken is cooked through and tender.
Adjust seasoning and serve hot with rice or bread.