For the tea syrup: Bring the water and sugar to a boil in a small saucepot. Remove from the heat and add the tea bags. Steep for 10 minutes. Remove the tea bags and let the tea syrup cool completely.
For the shaved ice: In a blender, combine the ice, water, lemon juice, limoncello if using, and all of the tea syrup. Puree until smooth.
Pour the tea ice into tumblers, and garnish with a lemon wheel and a mint sprig.