Put the teabags or tea leaves in 100ml boiling water and leave to brew for 10-15 mins. Discard the teabags or tea leaves, then set the tea aside to cool to room temperature. To make a clear sugar syrup, stir the caster sugar with 60ml water in a small saucepan over a medium heat and bring to the boil. Remove from the heat and leave to cool.

Bring 500ml water to a rolling boil in a small saucepan set over a medium heat, then add the tapioca balls. Using a rubber spatula, stir the water and make sure the balls, or boba, are not sticking to the side of the pan. Turn the heat up to reach a rolling boil for 2 mins, then turn off the heat, but keep the pan on the stove with a lid on for another 2 mins. Drain the boba in a sieve under gentle running tap water for about 20 seconds to slow down the cooking. Using the same spatula, gently push the boba around in the mesh to make sure they don’t stick and are cooling down evenly. Once they're cool to the touch, set in a mixing bowl, add the 1 tsp dark brown sugar and mix in thoroughly.

To make the sugar syrup, add the 50g dark sugar to 60ml water in the same pan set over a medium heat. Slowly stir and let it come to a boil, making sure all the sugar has dissolved. Turn off the heat and leave to cool down. It will thicken as it cools. This will make approx. 80ml syrup, about 2 1/2 servings. Any leftover syrup will keep in a jar in the fridge for up to a month. Add the cooked boba and mix until thoroughly coated. The boba can be left covered for up to three hours. Do not refrigerate as they will harden.

Assemble the bubble tea. Put the sweetened boba in a 485ml drinking glass, or two smaller glasses if you want to share. Swirl the boba to create a marble effect on the wall of the glass. Pour in the brewed tea and 1 tbsp of clear sugar syrup. Add 1/2 cup of ice and, using a metal spoon, stir the glass so the syrup and the tea are thoroughly mixed but make sure you don’t scrape off the sticky marbling effect on the wall of the glass. Top up with 200ml of cold milk and serve with a boba straw.