Pick your olives, choosing the fattest, darkest olives. Squeezing an olive should release a milky liquid if it's ripe enough to brine.
Once picked, if you have a real difference in colours, sort the green ones away from the black ones. The green ones are less mature and will need a little longer to brine and lose their bitterness.
Wash them well and remove any really damaged olives and dry shrivelled olives.
You can choose now to slit your olives, or leave them whole. Slitting each olive will allow the water and salt to penetrate it faster and remove the bitterness. If you leave them whole, they'll need to sit in a brine a lot longer.
To slit the olives, use a sharp knife to cut a little slit into each olive. Alternatively, you can carefully 'crush' your olives with a heavy object such as a meat tenderiser or a flat stone. Crush them enough to just break the skin but not to completely flatten the olives.
Now, give them an initial soak in plain water for a 2 days, changing the water each day. Keep the olives completely submerged in the water (use a plate or weight to hold them under).
Now soak the olives in brine using a ratio of 1 parts uniodized salt to 10 parts water.
Cover the olives with the brine , making sure the olives are again completely submerged. Loosely seal the jar or container with a lid. You will need to open it every couple of days to release some of the gases if the lid is on tightly.
If you have slit or crushed your olives, they will only need to sit in brine for 3-6 weeks depending on taste. If you have left them whole they can sit in brine for up to 6 months or longer.
How often you change the brine is dependant on your environment and how quickly they cure. Changing the brine weekly will leach the bitterness out faster, but if the olives stay submerged and there is no sign of mould, the brine doesn't need to be changed. It will slow down the process a bit, but it's a hands-off approach.If mould is growing, simply tip the brine out, rinse the olives and make fresh brine. Remove the lid and check the olives weekly.
Taste them after a month or two. If they are still too bitter, keep soaking them until you are happy with it. If they are very salty, don't worry for now. The main quest is to remove the bitterness.
Once the bitterness has gone, tip out the salt brine, clean the container and refill with fresh water. Soak the olives in fresh water for a 2 days to remove some of the salt.
Now it is time to jar up your olives in sterilised preserving jars.
I use a vinegar brine, at a ratio of 3 part salt, 10 part vinegars, 40 parts water. For example, 30g salt, 100g vinegar and 400g water makes about half a litre of vinegar/salt brine.
Add in any other flavourings you like such as lemon, lime, garlic, oregano, rosemary, chilli.
Cover the olives with the vinegar brine and flavourings. Ensure the olives are submerged under the brine. Pour over a little layer of olive oil which will stop oxygen touching the olives. Seal the jars, and let them sit for a week to infuse the newly added flavours before sampling.
Olives store well in a sealed jar for up 6 months in a cool dark place, or in the refrigerator for up to a year.