Put the sugar and water in a saucepan, and bring to a boil. As soon as the sugar dissolves, remove from the heat. Add the tea and allow to infuse for about 20 minutes. Filter and leave the syrup to cool. Wash the mint leaves, chop very finely and add to the syrup when it has cooled down.
In a large bowl, mix the milk and the yogurt or starter sachet, and then whisk until you obtain a smooth mixture. Add the green tea syrup with the mint and mix well.
Pour the mixture into the bottles. Place them in the yogurt maker and cook in yogurt mode for 6 hours.
Once the programme is complete, close the bottles if you have not yet done so and place them in the refrigerator for at least 4 hours. Shake well before drinking.