To a small saucepan over medium heat, add all the apple syrup ingredients.
1 (200 grams) large Granny Smith apple, 1 cup (240 ml) apple cider, 1/2 cup (120 ml) water, 1/2 cup (100 grams) light brown sugar, 2 cinnamon sticks, 1 teaspoon vanilla extract, pinch salt
Stir and bring to a boil while stirring frequently.
Reduce the heat to medium-low and cook for another 10 minutes or until the sugar has dissolved and the apples are tender, but not soggy.
Remove the pan from the heat and let the apples steep for 20 minutes.
Strain the syrup using a fine-mesh sieve, pressing down on the apples to extract all the flavor.
Let cool and then pour into an airtight container and chill.