Method
In a small bowl, whisk 3 tablespoons of hot water with 1 tablespoon of matcha powder until no lumps remain and a smooth, vibrant green paste forms.
In a large pitcher, combine 1/2 cup granulated sugar with 1/2 cup fresh lemon juice, stirring vigorously until the sugar is completely dissolved.
Pour the smooth matcha paste into the pitcher with the lemon-sugar mixture and stir thoroughly to combine into a uniform green liquid.
Add 4 cups of cold water to the pitcher and stir well until all ingredients are fully incorporated.
Fill serving glasses with 1 cup of ice cubes, pour the matcha lemonade over the ice, and garnish each glass with a fresh lemon slice.