Place the tapioca starch, 1 tablespoon fish sauce, salt and pepper in a bowl and stir to combine. Add the fish head and stir to coat. Set aside to marinate.
Meanwhile, to make the curry paste, place all remaining ingredients except coconut milk, lime leaves, longan and oil in a food processor and process until a coarse paste. Set aside.
Add oil to a wok and place over high heat. Add the fish heat and cook, stirring, until the fish head is partially cooked, about 3 minutes. Remove fish head from wok and set aside on paper towel.
Transfer the curry paste to the wok and fry until fragrant. Return the fish head to the wok and fry until cooked through, about another 10 minutes. Add the coconut milk, lime leaves and longan to the wok and stir to combine. Remove from heat and serve with rice and roti if desired.

MasterChef

East Malaysian Fish Head Curry