Remove the stems and leaves from the fruit and stone the cherries. Then the strawberries and cherries are cut into small pieces and poured into a large saucepan with the rock pears and the preserving sugar and mixed. If you want, you can also puree the fruit in a pot.
The whole thing must then boil and simmer for about 4 minutes (see also notes on the preserving sugar pack).
The jam is then poured hot into rinsed jars and sealed with a twist-off lid. Turn the glasses on their heads while they are still hot and let them cool down.
The quantities given relate to fruit that has already been prepared.
If you want, you can also mix in a little vanilla sugar.