In a small saucepan, combine the blackberries, water, sugar, lemon juice and zest and salt over medium heat.
Stir until sugar dissolves and then reduce heat and simmer on low for an additional 5-10 minutes. Using a potato masher, squeeze all of the juice out of the fruit.
Remove from the heat and allow to sit. The mixture might feel thin, it will thicken. Do not cook it until it is thick and syrup-like- it will be gelatinous when cooled.
Pour the mixture through a fine mesh sieve. You may be to stir or press it through because of the fruit fibers. Discard the solids.
Allow the syrup to cool and then use in a recipe or store in an airtight container at room temperature for up to a week.
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