Cook the rhubarb: In a saucepan, combine rhubarb, sugar, and water. Bring to a boil, then reduce heat and simmer for 10–15 minutes, until soft.

Blend it: Let the mixture cool slightly, then blend until completely smooth.

Strain (optional): For a silky texture, strain through a fine mesh sieve.

Flavor boost: Stir in lemon juice and optional vanilla or ginger.

Chill: Cool the mixture in the fridge for at least 1 hour.

Freeze: Pour into an ice cream maker and churn according to manufacturer’s instructions, or freeze in a container, stirring every 30 minutes for 3–4 hours to break up ice crystals.