Cut the strawberries and pineapple very small. Add all the ingredients and let it steep for about 1 hour over a very low flame, then bring to the boil and cook for about 8 minutes over high heat. Do the gelling test after 4 minutes. If necessary, add a little more preserving sugar.
Then immediately and hot fill everything into jars and after closing them with the lid, turn them upside down. Turn around after about 20 minutes and see if the glasses are closed.
If this is not the case, there is a good trick: clean the lid, put a little pure alcohol (2 drops) on the lid, ignite and immediately screw the lid with the little flame onto the glass. Now a vacuum should be created and the lid is tight! But be careful, risk of burns! Don`t use too much alcohol!