Combine black mission figs, sugar, lemon juice, and lemon zest in a heavy Dutch oven. Let stand at room temperature for 30 min to macerate as juices form and the fruit softens, stirring once halfway through so it releases evenly.

Add aged balsamic vinegar, fresh rosemary sprigs, and black pepper to the pan. Bring to a boil over medium-high heat, then maintain a steady boil for 2–3 min so the flavors start blooming.

Reduce the heat and simmer for 30–35 min, stirring often, until thick and deeply colored. Watch the jam’s slow movement on the spoon—when it holds a glossy trail, it’s ready.

Remove fresh rosemary sprigs and discard. Taste the jam and adjust sweetness as needed, then let it bubble 1 min on low to re-emulsify the flavor.

Test for set by dropping a small spoonful onto a cold plate and letting it stand for 30 sec. When it wrinkles slightly instead of pooling, ladle the jam into sterilized jars while hot, then cool before sealing.