Remove core from cabbage; shred as finely as possible (with a mandoline is best). Peel carrots, then peel into ribbons lengthways.
Combine the cabbage, carrot, rocket, mint and onion in a large salad bowl.
Shake the juice, balsamic condiment and oil in a clean glass jar; season to taste.
Just before serving, toss the salad with the Dressing in a large bowl with clean hands to avoid bruising the leaves.