I cure my olives at home and they are delicious! It's very easy and very safe.

Simply score each olive deeply, cover the olives with water and salt (about 1/4 cup salt for 1 quart of water) add spices if you wish, I love oregano, bay, and peppercorns, then put in large container with tight lid and "weight" the olives down with something so they are all submerged in the water (this is crucial).

Stir the olives about 2-3 times per week and remove any scum that forms on the water, making sure it doesn't touch the olives.

Change the brine solution once per week for about 8 weeks, then taste, if still too bitter, continue for several more weeks.