Start by sterilizing your jars: place the jars and lids in boiling water for 10 minutes, then let them drain upside down on a clean cloth.
Wash, hull and cut each fig into quarters.
Place them in a container, then add the sugar and the seeds from the vanilla pod. Mix well and let them macerate for 15 minutes so that the figs release their juice.
Pour the contents of the container into a large saucepan. Add the lemon juice.
Bring to a boil and stir occasionally with a wooden spoon. Cooking time is approximately 30 minutes (depending on the ripeness of the fruit).
At the end of cooking, give it a quick blast with an immersion blender if you don't want large chunks in your jam (that's what I do).
Tip: to know if the jam is set, pour a drop of the preparation on a plate taken out of the freezer. Then put the plate vertically: if the drop runs slightly then freezes, it's cooked enough! Otherwise continue cooking a bit.
Pour the jam into the sterilized jars. Close them and let them cool upside down to ensure proper sterilization.
Notes
Once the jar is opened, your fig jam will keep for around 10-15 days in the refrigerator.