1. Combine rhubarb, strawberries, and sugar in a large bowl. Stir well to coat, then cover and refrigerate for two days.
2. Add vinegar to mixture and whisk until sugar is dissolved. Set a fine-mesh strainer over a quart-size jar and strain mixture, pressing gently on strawberries and rhubarb to push out as much liquid as possible (discard solids).
3. Cover and refrigerate for up to six months.
Source: Hannaford fresh Magazine, May - June 2019