Cut each fillet into eight pieces. Marinate the fish fillets with salt, pepper powder and lemon juice for about half an hour. Dry roast the coriander seeds, peppercorns and red chillies till fragrant. Grind to a coarse powder.
Add thyme to this spice-mix. Heat sufficient oil in a non stick frying pan. In a bowl mix the spice powder, coriander leaves, cornflour and refined flour.
Coat the marinated fillets with the mixture and shallow fry on both sides until golden brown and crisp. Drain on an absorbent paper and serve hot.