Add the sugar and liquid to a medium saucepan. Stir to dissolve the sugar.
Add the agar agar and whisk thoroughly to combine.
Place the saucepan over high heat and bring to a boil. Whisk occasionally.
Once boiling, turn heat to medium and simmer for 4 minutes, whisking often.
Remove from the heat and whisk in the citrus zest.
Lightly spray a bundt pan or angel food cake pan with cooking spray.
Sprinkle the berries in an even layer within the bundt pan then pour the gelatin mixture over the berries.
Cover the cake pan with a lid or plastic wrap and place it in the fridge for 4 - 6 hours or overnight to become firm.
Once the congealed fruit salad is fully cooled and completely firm, lightly press on the top edges of the gelatin to loosen it. You can also gently jiggle the cake pan to help release it from the mold. Place a plate or cake stand upside down on top of the cake mold and carefully flip it over. The congealed fruit salad should release from the mold and be right side up on the plate or cake stand.
Top with vegan whipped cream, more fresh berries, or fresh mint leaves if preferred and serve! Store any leftovers in an airtight container in the fridge for up to 4 days.