Grate the quinces, wash and chop them. Boil up with 1 1/2 l water. Simmer covered for about 1 hour
Place the moistened gauze cloth in a large sieve. Pour the quinces together with the liquid on top. Drain for about 12 hours, e.g. overnight.
Measure out 900 ml of juice. Carve the vanilla pod, scrape out the pulp. Mix with juice, vanilla pod and jam sugar in a large pot. Bring to the boil at high heat, stir continuously and boil for 3 minutes until bubbly. Immediately fill into prepared twist-off glasses, close them, let them cool down