Clean the sardines by cutting the heads and tails off with a scissors. Then, cut down the backbone to open the fish. Do not slice completely through. Remove the bone.
Coat the insides of the sardines with a covering of gray salt and close the fillet. Coat the outside with salt, and place in a shallow, small plate. Cover and place in the refrigerator for 12 hours.
Rinse well and slice in half to separate the fillets.
In a small bowl, whisk the lemon juice, olive oil, and oregano together. On a platter, lay the tomatoes out and place the sardine fillets on top. Pour the lemon mixture over the fish. Toss olives on top and serve with the rustic bread for meze.
Recipes courtesy Cat Cora