Add the mulberries and 1/2 cup of water to a blender. Blend until smooth.
Pour the mixture through a fine mesh strainer or cheesecloth to remove seeds and pulp, especially if you prefer a smooth drink.
Squeeze your lemons to get fresh juiceāremove seeds but keep the pulp for extra flavor.
In a small saucepan, combine sugar (or honey) with 1/2 cup of water. Warm it until fully dissolved to make a simple syrup. Let it cool.
In a large pitcher, combine strained mulberry juice, lemon juice, simple syrup, and the remaining cold water.
Stir well and taste. Add more water, lemon, or sweetener if needed, depending on how tart or sweet you like it.
Pour into glasses over ice. Garnish with lemon slices and mint if desired.