First chop the fruit thoroughly with a hand blender and add the grape sugar and the vanilla aroma as well as the gelation fix. Then put the pureed mass in a saucepan and cook for about 3 minutes (note the instructions on Gelierfix). Pour the jam into jars while hot and place on the lid. In the case of severe fructose intolerance, it is better to use raspberries or blueberries instead of strawberries, as these are usually more digestible. Depending on the taste, however, a little more glucose (or sweetener) must be added, since these berries are not as sweet as strawberries.