1. Begin by asking the fishmonger to fillet the sardines for you, otherwise, clean them by removing the entrails, and heads, and giving them a thorough wash.
2. Wash the sardines’ fillets with cold water, strain them, and let them dry.
3. Place them in layers next to each other in a bowl, cover them with salt, and let them sit for 24 hours.
4. Then, drain the liquid that the sardines have released but leave the salt on them.
5. Layer the sardines again, this time covering them with the vinegar, and let them sit for another day.
6. The following day, remove the vinegar and carefully clean each sardine fillet, removing the backbone.
7. Place the cleaned sardines in a glass jar and cover them with olive oil.
8. Serve them drizzled with olive oil and a squeeze of lemon.

Source www.imommy.gr & www.tovima.gr