To make this lovely drink here is what you do:
25ml St. Germain elderflower liqueur
2 springs of mint
1/2 a lime
In a large highball glass, place 1 spring of mint and 1/4 of the lime in the bottom. Using the end of a rolling pin, bash the mint and lime together. Fill the glass up with ice and add the gin, elderflower liqueur and top up withe apple juice. Garnish with the other sprig of mint and lime wedge.
If you don't have St. Germain elderflower liqueur use elderflower cordial. This is also delicious as a non-alcholic version using elderflower cordial and omitting the gin. Idea from here.