- Add the blackberries and lime juice to a pan over medium heat and bring to a boil for 5 minutes or until the blackberries are softened.
- Transfer blackberries to a bowl and mash with a fork.
- Place a fine mesh sieve over a bowl and pour the mixture in and use a spoon to press out all of the juice from the blackberries. Discard skin and seeds afterwards.
- Add the powdered Erythritol to the blackberry syrup and stir until combined. Refrigerate syrup until ready to use.
To create the cocktail:
- Fill each glass with ice and pour in 1/4 cup of vodka.
- Add an equal portion of the blackberry syrup mixture.
- Gently stir. Top with some sparkling water.
- Optionally, garnish with a lime wedge.
This recipe makes enough syrup for 5-6 cocktails.