At the beginning, clean, wash and drain the strawberries. Then cut into small pieces and place in a large saucepan with the remaining ingredients. Bring to the boil over high heat while stirring. Cook for at least 5 minutes, stirring constantly. Skim off any foam that may have formed. To be absolutely sure how long the whole thing still has to cook, do a jelly test.
Immediately pour the jam into clean twist-off glasses. Close the jars and place on the lid for about 5 minutes. Turn again and let cool down.
The amount is enough for 6-7 glasses. The jam should be stored in a dark and cool place.