Combine 400ml of filtered water with 2-3 teaspoons of Sirocco vanilla black tea in a clean container. Stir gently, cover, and refrigerate for 8 hours.

In a small saucepan, dissolve 15g of granulated sugar in 200ml of warm water over low heat. Once dissolved, cool it and mix in 50g of freshly squeezed lemon juice.

Fill a tall glass with ice cubes. Pour 150ml of the prepared lemonade over the ice, then add the cold-brewed vanilla black tea to fill the glass.

Garnish with fresh lemon slices as desired, either on the rim or floating in the drink.

Store any remaining vanilla black tea in a sealed container in the fridge for up to one week.