In a saucepan over low heat, add the strawberries, basil, and water.
Simmer for about 15 minutes until the strawberries begin to break down and release their juice.
Using a mesh strainer, strain out the liquid from the fruit. Use a spoon to press the mixture against the strainer to extract more liquid. Discard the fruit mash.
Add the apple cider vinegar to the fruit juice and store in the fridge for up to 1 month.
To make the soda, mix about 1 tsp of the strawberry vinegar to the carbonated water, and adjust the ratios to taste.
Notes
Feel free to adjust the ratio of apple cider vinegar if the drink is too strong. You can also add a sweetener if you prefer the soda sweeter. Adjust the about of syrup you add to the carbonated water to your taste preferences also.