Cut 1 lime, 1 lemon and 1 orange in half. Squeeze juice of each into the pitcher. Add simple syrup and Gran Mariner. Stir to combine.
Thinly slice 1 lime, 1 lemon and 1 orange. Add to pitcher along with fresh berries.
Place in refrigerator for 3 hours (or overnight).
To serve, put ice in a glass, pour White Sangria over top. Top with a splash of tonic water and garnish with fresh mint and additional fresh berries (frozen berries would work too).
Notes
Serving Right Away: If serving right away feel free to add ice to the pitcher after it sits for 3 hours or you can add some frozen berries instead of ice to help keep it cool.
White Wine Recs: we used a white wine blend but a pinot grigio or sauvignon blanc would be great!