Speed peel the zest of 1 orange into a heatproof jug or pitcher. Add the tea bags, 1 tablespoon of sugar and 600ml of just-boiled water, stir, then leave to steep for 5 minutes.
Remove the teabags and pour in 500ml of cold water, then leave to cool to room temperature, before placing the jug in the fridge for at least 1 hour.
Meanwhile, to make the cherry syrup, wash and pit the cherries, placing them in a medium saucepan as you go. Add the remaining sugar, squeeze in the juice of the peeled orange and simmer on a medium heat for 10 minutes, or until the cherries are soft and syrupy.
Turn off the heat and mash the cooked cherries with the back of a spoon, then pour it through a coarse sieve into a large bowl, pushing all the juice through with the back of a spoon, discarding the pulp.
Set aside to cool completely.
When you’re ready to serve, add the cherry syrup and apple cider vinegar to the iced tea and stir well. If you like it sweeter, you could add a little honey, if you like.
Fill 6 tall glasses with ice cubes and orange slices, pour over the cherry iced tea and serve.