Rinse and wipe dry the fish fillets.
Dry-fry the fennel, coriander, cumin seeds and peppercorns in a pan. When fragrant, move them to a stone mortar, add the cinnamon and crush into a coarse powder with the pestle. Add the salt, oil, minced garlic, lemon zest, cayenne & paprika and mix until you get a coarse paste.
Rub the paste into the flesh of the fish - not on the skin. Chill for two hours in the fridge.
Set a barbecue, grill or griddle pan to medium heat.
Brush the skin of the fish with olive oil, then place them skin side down on to the BBQ/grill/ griddle.
After 1-2 minutes carefully turn them over and fry for another 1-2 minutes.
Serve with a few drops of lemon juice squeezed over them and some coriander leaves scattered around.