Take a hike along paths in the country side or up hill and find wild brambles. Do not forget to wear boots or sneakers, long sleeves sweater and gloves. Walk and breath the clean oxygen ...
.... of the place. Giglio Island can be THE PLACE and, believe, it is the best one for wild blackberries.
Pick the darkest berries. Put them in a basket. Never in a plastic bag.
Go home, weigh and wash them.
Weigh the sugar. My personal ratio is: 3/4 of the weigh of the blackberries.
Put the berries and part of the sugar ( let's say 1/3 of it) in a pan.
Cook about 10 minutes, crushing the berries with a spatula until they have produced some liquid and they are softer. Like this photo below:
Pass the mixture through the Italian Passaverdura (food mill):
Once you have collected the mixture, pass it again through a thinner sifter, called Passamore. You see in the photo below:
Put the sifted mixture in a pan with the remainig sugar. Let it simmer until it reaches 108°c ( 227 F).
As still hot, with a ladle fill glass jars. Close tied with their caps. Place the jars upside down. In this way the vacuum would form.
A safer way is to boil them until you hear the "clic" of the cap once the vacuum forms inside the jars.
Boiling glass jars means to wrap them in cloth, before putting them in a pot and filling it with water, to prevent them breaking as they shake with the rollng boiling water.
It is very good on Pecorino cheese. Great to make Crostata, especially if the pastry is made with tasty flours like buckwheat, farro, grano arso .....
Super on a toast with butter for breakfast......