In a bowl, combine the grated apples, vinegar, sugar, and cinnamon, stirring or shaking to evenly coat the fruit.

Cover tightly and refrigerate for 24 to 48 hours.

Give the mixture a gentle press with a wooden spoon or muddler, then using a fine-mesh sieve, strain the liquid from the pulp, and transfer the liquid to a clean glass jar.

The shrub will be ready to drink in 1 week and keeps for up to 6 months in the refrigerator.