For 3 jars of one kilogram we will need:
3 pounds grapes
1.5 kg sugar
3 branches of marjoram
Juice of one lemon
Clean and rinse the grapes. In a large pot, we alternately lay a layer of grapes and one layer of sugar. Let them boil over low heat. When the sugar melts, put the marjoram in a tulle and put it in the pot. When our sweet colour changes, add the vanilla and lemon and leave to boil until the syrup is ready. The syrup is ready when we drop a drop on a plate and does not dissolve.