Prep the Fruit:
In a large bowl, combine the raspberries, blueberries, blackberries, chopped peach, halved grapes, and drained mandarin oranges.
Make the Simple Syrup:
Set a saucepan over medium-low heat (around 3 to 4 on the stove dial).
Add the 1 cup of mandarin orange juice liquid and ½ cup dark brown sugar.
Stir for 3–4 minutes until the sugar completely dissolves.
Stir in the chopped fresh mint and bring the mixture to a boil.
Once boiling, reduce to a simmer and let it cook for about 5 minutes to infuse the mint flavor into the syrup.
Cool the Syrup:
Remove the syrup from heat and allow it to cool completely (place it in the refrigerator for about 10 minutes so it doesn't warm the cold fruit).
Optional: You can strain out the mint leaves if desired, or leave them in.
Macerate & Chill:
Pour the cooled mint simple syrup over the fruit mixture.
Gently stir to coat the fruit.
Cover the bowl with plastic wrap and chill in the refrigerator for a couple of hours to allow the fruit juices to release and macerate.
Serve:
Spoon into serving bowls and garnish with extra fresh mint leaves if desired.
