Brew the mint tea bags with 2 cups of water, and let cool.
Meanwhile, prepare the watermelon for juicing. Slice the watermelon into medium sized chunks, filling the blender about 2/3 of the way full. Blend until smooth, adding more watermelon chunks if necessary until you reach at least 3 cups.
Place a mesh strainer over a bowl and pour the watermelon juice through the strainer, stirring with a spoon to strain.
Once you've reached 2 cups of strained watermelon juice, combine the juice and tea in a pitcher, and stir to mix.
When ready to serve, pour into 2 glasses over ice, and garnish with mint if desired.