Half- or quarter-pint Mason jars with two-piece lid closure
Tall stockpot with a lid and silicone blossom trivet (available online) for processing
Clean kitchen towel
Wide-mouth canning funnel
Large nonreactive bowl
Small stainless steel skillet
Mortar and pestle or spice grinder
To toast the fennel seeds, heat them in a bare stainless steel skillet until they’re aromatic and just start to darken. This won’t take more than a couple of minutes. Use a mortar and pestle or spice grinder to grind them into a coarse powder.
In a large nonreactive bowl, fold together the figs, sugar, and lemon juice. Add the fennel seeds and let the mixture macerate for at least 4 hours or up to overnight.
Transfer the mixture to your preserving pot using a spatula to scrape any sugar that has settled to the bottom of the bowl and, over high heat, bring to a boil that can’t be stirred down.d
Cook for about 7 minutes, or until a dollop of jam placed on saucer and cooled for a few minutes in the freezer doesn’t run back together when you drag your finger through it. Remove from the heat and stir in the balsamic vinegar.
Ladle into prepared quarter-pint jars, leaving ¼-inch headspace. Remove air bubbles and wipe rims. Place the lids on the jars and screw on the bands until they are fingertip tight.
Process in the tall stockpot with lid for 15 minutes, adjusting for altitude as needed. (At 1,000 to 3,000 feet, increase processing time by 5 minutes. At 3,000 to 6,000 feet, increase processing time by 10 minutes.)
After 24 hours, check the seals. Label, date, and store out of direct sunlight without the bands for up to a year.