Slice the oranges and lemons in half. Squeeze the juice into a measuring cup until you have at least 2 cups of orange juice and 1 cup of lemon juice. Strain the juice through a fine mesh sieve to eliminate pulp and seeds.

In a large pitcher, combine the orange juice, lemon juice, and simple syrup. Add cold water, adjusting sweetness to your liking. Stir vigorously for about 30 seconds.

Let the pitcher chill in the refrigerator for at least 30 minutes. Serve over ice and garnish with slices of orange and lemon along with a sprig of fresh mint.