Put the salt, sugar, and all other aromatics in a bowl and mix well.

Prepare the mackerel fillets (remove pinbones if they're large), then pat them dry. (Here’s a link if you've bought a whole fish and need help filleting them.)

Place a third of the curing mix in a shallow tray/container, then carefully position your mackerel fillets on top of the curing mix, skin-side down, avoiding any overlaps. Distribute the remaining cure evenly on top of the fillets. Leave to cure in the refrigerator for 2-3 days.

Wash off the excess salt from the mackerel fillets and pat them dry. To help them dry off, you can put them in a dehydrator, or in an oven at a low temperature (~50°C) overnight.

To store, keep in an airtight container/mason jar submerged in olive oil (or any neutral oil works fine too).