In a 6 litre pot combine sugar and 1.7 litres water. Bring to boil and stir until sugar dissolves. Remove from heat. Stir in tea powder while hot. Add orange juice, lemonade concentrate and 500ml cold water. Chill in refrigerator.
When cold mix in vodka. Pour into a plastic container leaving room on top for expansion. Freeze or 24 hours.
To serve, scoop about 250ml into a tall glass and quickly stir in 75ml lemon-lime fizzy drink.