Apricot preserves

Rinse, pit and weigh the Jolife apricots. Add 400 g of sugar for each kg of fruit. Transfer the apricots to a pan with the zest and juice of half a lemon. Bring to a boil over medium heat. When the mixture starts boiling add the sugar. Return to a boil. Continue cooking the preserves for about 40 minutes. To test the thickness, pour some preserves on a small dish and put in the freezer for 5 minutes; the preserves is ready when it does not run when you tilt the dish. Pour the preserves in sterilized glass jars while still boiling hot, seal and let cool with the jars upside down in order to create a vacuum seal. Keep the preserves in a cool place.