Combine rhubarb, sugar, and water in a medium saucepan.

Bring to a simmer over medium heat, stirring occasionally.

Reduce heat and cook for 10–15 minutes until rhubarb breaks down and mixture thickens.

Stir in lemon juice and vanilla (if using).

Let cool and store in a jar in the fridge for up to 1 week.

Spoon over yogurt, oatmeal, pancakes, or ice cream.

Swirl into cheesecake or toast with ricotta.