Place the horse mackerel with its head to the left and belly facing you. Scrape off the scales from tail to head on both sides.

Cut behind the pectoral and ventral fins diagonally, reaching the backbone. Flip the fish and repeat on the other side. Remove the head.

Make an incision along the belly from the vent to the head. Remove the guts and clean the blood membrane thoroughly.

Slice along the backbone from head to tail to separate the fillet. Flip the fish and repeat on the other side.

Remove the rib bones by slicing thinly along their base. Use tweezers to pull out any remaining bones.

Peel off the skin by gripping the edge and sliding the knife between the skin and flesh.