1. Heat oil in a wok or pan over a medium high heat.
2. Add the shallots, garlic, ginger and chilli. Cook until soft and golden.
3. Add the whole cherry tomatoes along with the chilli powder, tomato puree, rice vinegar, palm sugar and fish sauce.
4. Cook over a medium heat until the tomatoes start to burst and the sauce consistency becomes jam like. This will take about 5 minutes or so.
5. On a plate, mix cornflour, chilli powder, salt and pepper. Dust the fish on both sides.
6. In a separate frying pan, heat three tablespoons of oil. The oil needs to be very hot.
7. Add the fillets to the pan, skin-side down. Cook for 2-3 minutes on each side. The skin should be nice and crispy.
8. To serve, place some of the sauce on a serving plate, place the crispy fillets on top and spoon over more sauce. Sprinkle with coriander, spring onions and serve with a wedge of lime.