Using a sharp knife, carefully peer your purple yams and then rinse them under cold running water.

Chop them into large pieces and then place in a pot: add just enough water to cover the chunks and bring to a boil.

Let the yam cooked until tender, then drain and place in a tall milkshake blender. Let it cool.

Using the same pot you cooked the yam in, heat up your condensed milk, milk of choice and sugar: let them cook until they form a smooth drink and add them to your blender.

Close carefully and then blitz until they turn into a smooth drink. Let is cool.

Take a clean pan and bring water to a boil. Add your tapioca balls and let them cook following cooking instructions: they are ready once they are black and floating gently.

Use a strainer to train the water, the run your tapioca balls under cool running water to stop the cooking process and cool them down.

Now you can assemble your drink!

In a tall glass, add your boba balls, the milky mixture and finally ice cubes. Add a chunky straw and serve!