Combine the thyme, ground cumin, chilli flakes, olive oil, and garlic in a food processor and pulse until it forms a paste. Alternatively, use a mortar and pound with a pestle until paste-like.
Add the honey to the paste and stir to combine. Rub the paste generously on the fish, and put some of the paste on the inside of the fish. Wrap in clingfilm and leave in refrigerator to marinade overnight.
When ready to grill, remove fish from refrigerator and allow to come to room temperature. Oil the grill grates and pre-heat the grill to 220* centigrade.
Brush a small amount of oil onto the skin of the fish and apply a generous amount (to your taste) of salt and pepper to the skin and the inside of the fish. Grill for 8 - 10 minutes on each side before turning over once. Repeat on the other side.
Serve with a slice of lemon and some vegetables or pilau rice.