Heat oil in a deep saucepan. Add onions and fry until golden brown. Add the garlic ginger paste, chilli powder, coriander, cumin, garum masala, cinnamon stick, cardamom pods, cloves and peppercorns and 2 tablespoons water.
Fry, adding 2 tablespoons water as necessary, until the oil separates out from the curry sauce, about 10 minutes. Add the chicken and 1/2 cup water and simmer 25 minutes. Cover, reduce heat to low, and simmer until chicken is done. Add salt to taste.