In a cocktail shaker or glass jar, add dragon fruit, lemon juice, and sweetener of choice. Using a muddler, smash all of the ingredients together (for a smoother consistency, blend in a blender until smooth and creamy). Strain mixture evenly into the glass. Add vodka, St. Germain, and ice. Top with sparkling water or ginger beer; gently stir, and garnish with fresh lime. Enjoy!