In a 4-cup measuring cup, place 1 cup cold water and then sprinkle in 1 packet unflavored gelatin. Do not stir. Separately, steep 3 bags of the tea of your choice in 2 cups boiled water for 3 minutes. (Adjust the amount of tea to achieve your preferred thickness.) Add tea to gelatin and stir well.
Note that it will be thin when warm, and get thicker the longer you chill it. If it gets too thick, just add some warm water or tea.