Heat the oil in a wok or saucepan. Stir-fry the curry paste over a medium heat for 3–4 minutes or until fragrant.
Add the coconut milk, fish sauce and sugar or honey and simmer gently for 2–3 minutes or until the sugar has dissolved.
Add the fish fillets and the tamarind purée or lime juice. Splash the sauce over the top and cook for 4–5 minutes or until the fish is done, moving it occasionally. The sauce should be slightly mild, sweet and sour to taste, not too hot. Taste and adjust the seasoning.
Spoon on to 4 warm serving plates and garnish with kaffir lime leaves and chilli slices.