In a saucepan, combine cherries and water. Bring to a simmer over medium heat and cook for 15-20 minutes.
Strain through a fine mesh sieve, pressing gently on the solids to extract more liquid. Discard the solids.
While the cherry liquid is still warm, stir in the sugar until completely dissolved. Let cool to room temperature, then refrigerate.
Make the limeade
In a large pitcher, combine the lime juice, cold water, and vanilla extract.
Add the cooled cherry syrup to the limeade and stir well. Taste and adjust — you can add a little more water if you prefer a lighter flavor. Refrigerate 1 hour.
Pour over ice and garnish with cocktail cherries and lime slices.
Notes
Lime juice notes: Fresh juice is worth the effort. I’ve tried this with both lime juice concentrate and fresh lime juice, and the fresh is so much better. If it is too tart, you can add more syrup and/or more water. Be sure to strain the lime juice before making the limeade so that there is no pulp or chunks. You’ll have a smooth and tasty drink!Serving suggestion: Refrigerate this drink for at least an hour before serving. The colder it is, the better the flavor! Make it by the glass: If you are using store-bought limeade with cherry syrup, you can use this ratio: