Pick only those that are unblemished and firm. You will need a 2-gallon crock.
5pounds firm green or purple olives
Pinches of thyme, orégano, and savory
Pick over the olives and remove any that are heavily bruised.
If the olives are green, place a handful on a clean kitchen towel, fold to cover, and gently tap each olive with a rolling pin, pestle, or smooth stone. (The cloth will absorb the olive juices and soften the impact from the cracking.)
If the olives are tan to purple or green to purple, place a handful of olives on a clean kitchen towel and slit each one on one side with a small sharp knife.
Place the cracked or slit olives in a large plastic bucket or a deep earthenware crock and cover completely with cold water and a loose-fitting lid. Store in a dark cool place and change the water twice a day until the olives no longer taste bitter, about 1 week. (Bitterness varies with the variety and ripeness of the olive.) Use a wooden spoon to remove an olive for testing. Discard any mushy olives.
When the olives no longer taste bitter, make a saltwater brine. It should be strong enough to float an egg: mix 3 quarts water with ¾ cup sea salt. Wash and dry an egg. Place it in the solution. It should just float—that is, a small part of the egg’s surface about the size of a half dollar should rise above the liquid. If the egg doesn’t float, add more salt.
Rinse the olives in a colander under cool running water, drain, and slip into the prepared brine. Place a clean cloth over the brine and olives. Cover with a lid and store in a cool dark place for 6 months. If scum appears, remove and discard. The olives are now ready to eat.
If you wish to keep the olives longer, drain them. Repeat with a fresh salty mixture and keep for up to another 6 months. About 3 to 4 days before serving, remove the amount of olives you wish to use. Place in a clean bowl, cover with fresh water, and soak for 1 day, changing the water 2 or 3 times. Season the olives with dried herbs or the quince dressing and store in the refrigerator for up to 2 days. Serve at room temperature.