Place the berries in a small bowl and mash them into a purée. Set a few whole berries aside for garnish.
Pour freshly squeezed lime juice into a glass or shaker and mix it well with either elderflower or agave syrup.
Hand-pluck the mint leaves and add them to the lime juice along with ice cubes. Then, shake or stir the mixture vigorously.
Fill the three serving glasses with the berry purée first, and then top them off with the lime-mint mixture.
Now, carefully stir in the sparkling mineral water and cream soda.
Here's an optional tip from the hotel bartender: "If you like it spicy, add a splash of chili or ginger syrup. It gives the lemonade a cool kick that perfectly balances the fruity sweetness."
Garnish & Serve: Garnish with fresh berries, lime slices, and mint leaves. Sprinkle a pinch of sea salt on top for an added kick that perfectly rounds out the flavor and enhances the fruitiness.