Whisk a little icing sugar and lemon juice into your apple juice to get the right balance of sweetness and acid, remembering that when frozen the power of both sweetness and acidity are diminished.
Then either churn in an ice cream maker or pour into plastic dishes to a depth of no more than 2cm/¾in. If you're using plastic dishes, then remove them from the freezer when the mixture is just frozen (but not rock hard) and scratch up into a soft sorbet using a fork - if you've never tried this method you'll soon get the hang of it.
Either serve straightaway or pack into tubs and freeze. Defrost for 30-60 minutes at room temperature before serving.
Serve with a couple of tsps of calvados over the sorbet.