Preheat the oven to 180 ° C (top / bottom heat, convection: 160 ° C). Remove the core of the apples with an apple cutter.
Place the apples on a baking sheet lined with baking paper and cook on the middle rack for 5 minutes. Then put the cinnamon and star anise on the tray. Cook for another 10 minutes, until the apples are soft but not yet burst. Let cool down.
Halve the vanilla pod lengthways. Scrape out the pith. Peel the lemon peel thinly with a peeler.
Put the apples with the spices, vanilla pulp and pod, lemon peel and rock candy in a mason jar that has been rinsed with hot water. Top up with grain. Close tightly and let steep for 4 weeks.
Strain the finished liqueur through a coarse sieve and then filter through a cheesecloth. Fill into bottles and close tightly.