Cook the isomalt and the water in a small saucepan to 145°C / 293°F. Stir in the balsamic vinegar carefully to avoid splattering.
Pour onto a nonstick rubber mat and place another nonstick rubber mat on top. Roll out as thinly as possible with a rolling pin. Let the isomalt cool on the nonstick rubber mat, then place it in a warm oven to make it pliable again. This step will create hundreds of small bubbles in the croquant, which will make it very visually appealing.
Once the sugar is pliable again, start pulling it as thin as you can with your fingers. If there are thick pieces, they will be impossible to eat; they should be as thin as a sheet of paper (or thinner if possible).
Place each pulled piece on top of a curved surface, such as a rolling pin or wooden dowel, while it is still warm and pliable, to give it a curved shape. The croquant will cradle the ice cream. Try to obtain similar-looking pieces (it will be impossible to make them identical). If it hardens too much, they can be softened in the oven again for a few seconds.
These pieces are very fragile. Reserve in a sturdy airtight container and handle very carefully. Use silica gel packs to absorb any moisture in the container. If properly stored, they can last indefinitely.