Any bramble fruit, fresh or frozen, wild or store-bought, will work with this recipe. Blackberries, blackcap raspberries, regular raspberries, dewberries, cloudberries, salmon berries, thimbleberries, etc. My method works really well for any normal kitchen. But, for those of you with fancy juicers, you can pretty much make an instant puree/juice from your blackberries. Just measure out equal parts blackberry juice to sugar, heat the mixture to dissolve the sugar, then strain and put in jars.
Pour the blackberries into a saucepan and turn the heat to medium. Pour the sugar all over the berries, but do not stir. Let the heat begin to break the blackberries before stirring gently, about 5 minutes.
Stir every five minutes, just to keep anything from burning on the bottom of the pan. Let the blackberries melt with the sugar slowly, about 15 to 20 minutes. Turn off the heat, and mash the berries with a potato masher. You don't need to wail on them, but you want to get as much juice as you can.
Set a very fine-meshed sieve over a large bowl. Carefully ladle out some free-run syrup, which will be beneath the floating blackberries. Pour it through the sieve. Keep doing this until you have all the blackberries in the sieve. Let this drain for 1 hour, or up to overnight in the refrigerator. Once the berries are in the sieve, do not mash them, or you will get cloudy syrup.
Pour off the syrup into jars and either keep in the fridge or seal in a hot water bath for 10 minutes. Oh, and the leftover blackberries? Mix them with plain yogurt and they are delicious!
Some people want a less-sweet syrup, which is perfectly fine. You can add sugar to taste if you want. The tradeoff is longevity. If you don't use this much sugar, your syrup will not store as long; sugar is a preservative. Done my way, this syrup will store in the fridge a long time, easily a year or more.