Prepare your jars by rinsing them and the lids with boiling water. Let them dry on a rack.
Peel the pears, remove the cores and quarter them. Chop the quarters into tiny cubes and put them in a pot. (You can use the peels and cores to make pear vinegar, just like this recipe for apple vinegar).
Squeeze the lemon and add its juice to the pears.
Cut open the vanilla pod lengthwise and scrape the vanilla pulp out with your knife. Add both, the pulp and the pod to the pears.
Add the sugar to the pot and mix everything well together. Let it rest for 24 hours.
After that time, remove the vanilla pod and add the pear brandy.
Bring the mixture to a biol while constantly stirring. Make sure that it doesn't stick to the bottom of the pot.
Once the mixture come to a boil, set your timer and let it boil for 4 minutes.
To test if it's ready, ladle a spoonful of the jam onto a plate. Tilt the plate so that the hot jam runs across its surface. It should thicken as it runs across the cool plate.
When the jam is ready, ladle it into the clean jars up to about one cm under the brim. Close the lids tightly and put the jars upside down onto a dish towel on the counter. Let them cool down and label the jars.
