Place vinegar, maple syrup and herbs, if using, and blackberries in a small saucepan, gently crush some of the berries with your fingers or back of a spoon, bring to a boil, once boiling reduce heat to low.

Allow glaze to gently simmer, stirring occasionally.

When glaze has reduced by ⅓ to ½ and costs the back of a spoon, remove from heat and allow to cool slightly.

Pour glaze through a fine mesh strainer to separate glaze from the berries and herbs.

Place the separated berry mixture in a separate container and use as a jam.

Both will thicken as they cool. Store both on an airtight container in your fridge.