Grate and rinse the quinces with a dry tea towel. Grate with the Bircher raw vegetable grater. Mix with the sugar. Leave to stand for 24 hours.
Press the quince puree through a sieve, reserving the juice.
Pour quince juice and remaining ingredients into a bottle with a stopper. Put the bottle in a light place for 14 days and shake it heartily once a day.
Filter the contents of the bottle, i.e. pass it through a fine crockery or paper coffee filter.
850 ml of juice (960 g) (550 ml through a sieve, the rest through a dish strainer).