01 -
Trim the rhubarb stalks and cut them into small pieces.
02 -
Combine rhubarb pieces and water in a large saucepan. Bring to a simmer over medium-high heat and cook for 10 minutes or until rhubarb is very soft.
03 -
Strain the mixture through a fine mesh strainer over a medium saucepan, pressing to extract maximum liquid. Discard or reserve solids for another use.
04 -
Add vanilla seeds and pod (or vanilla extract, if using), lemon juice, lemon zest, and granulated sugar to the strained liquid.
05 -
Bring to a simmer over medium-high heat and cook for 10 to 15 minutes, stirring occasionally, until a syrup consistency is achieved. Remove vanilla pod if used.
06 -
Transfer the hot cordial into a sterilized jar or bottle, seal well, and allow to cool at room temperature.