01 -
Place the ice cream machine canister in the freezer for at least 24 hours to ensure it is frozen solid.
02 -
Combine rhubarb, water, and honey in a small saucepan. Cook over medium heat, stirring until rhubarb releases its own juices. Reduce heat, cover, and cook for about 5 minutes, stirring occasionally, until rhubarb is soft but still chunky. Remove from heat, add vanilla and rosewater if desired. Let cool, then chill for 3–4 hours or overnight.
03 -
In a large saucepan, whisk one can of coconut milk with arrowroot starch and salt. Heat over medium-high, stirring constantly until bubbles form and the mixture thickens. Remove from heat. Whisk in honey and add the remaining coconut milk and vanilla. Mix until smooth. Chill in a container for 3–4 hours or overnight.
04 -
Pour the chilled ice cream base into the ice cream maker canister. Add ⅓ of the rhubarb mixture to the base to mix throughout. Churn according to the manufacturer's instructions.
05 -
Add the remaining rhubarb mixture near the end of the churning process, allowing it to mix without breaking the chunks.
06 -
Eat immediately for a soft-serve texture, or transfer to a freezer container and freeze for 3–4 hours for a firmer consistency. Allow the ice cream to soften for 25–30 minutes at room temperature before serving if frozen solid.