Toss the strawberries with the sugar and let sit for 10-15 minutes then lightly mash them with a fork. Cover and refrigerate for a day, stirring once or twice.
Strain through a fine mesh sieve set over a clean jar, pressing on the berries to extract every bit of juice. Stir in the vinegar, seal, and refrigerate for 2 days.
To serve, pour 2 tbsp shrub over ice and top with soda water. It is also lovely topped with sparkling wine.
