Step 1

Mix rhubarb, vinegar, and granulated sugar in a small saucepan over medium-high heat, stirring as the rhubarb begins to break down.

Step 2

When the mixture comes to a boil, reduce heat to low and cook until the rhubarb is completely broken down into a jammy consistency, about 15 minutes, stirring occasionally.

Step 3

Remove from heat and pour into a fine-mesh strainer. Allow the mixture to strain until it stops dripping about 20 - 30 minutes. You can stir the mixture gently once or twice to help it strain, but do not press on it. (Save the solids and use them as a flavoring for yogurt, ice cream, or as a rough jam for toast. Alternately stir the rough jam into a muffin mix and make rhubarb muffins or rhubarb bread.

Step 4

Pour the resulting shrub into a mason jar or cruet and store in the refrigerator.