01 - If using sugar, prepare a simple syrup by heating 1/2 cup water and 1/4 cup sugar in a small saucepan over medium heat until sugar dissolves completely. Let cool before using.
02 - Combine mango, strawberries, and lemon juice in a blender. Blend until completely smooth and no fruit chunks remain.
03 - Pour the fruit puree through a fine mesh sieve into a pitcher to remove seeds and pulp for a smoother lemonade consistency. Press with a spoon to extract all liquid.
04 - Add the cooled simple syrup (or sweetener of choice) and 3 cups cold water to the pitcher. Stir thoroughly to combine all ingredients.
05 - Taste the lemonade and adjust sweetness by adding more sweetener if desired, or add more water if the flavor is too intense.
06 - Fill glasses with ice cubes, pour lemonade over ice, and garnish with fresh mint leaves and fruit slices. Serve immediately while cold.