Place the rhubarb and sugar in a medium bowl and stir to combine.
Cover the bowl with foil and place in the fridge to macerate for 2 days.
After two days, position a fine mesh strainer over a small bowl and pour the mixture through to remove the solids. Save for another use or discard the solids.
Combine the strained syrup with the vinegar in a pint jar and shake to combine and help dissolve any extra sugar.
Serve topped with soda water to taste and store in the fridge.
Notes:
This really does make a small batch, right around a half pint. Of course, it can easily be scaled up if you have more rhubarb to invest and you already know you’re a fan of shrubs.
Your final product will not suffer if the rhubarb macerates for a bit longer than two days.