To Make the Sauce for the Swirl:

1. Place rhubarb, sugar, and water in a medium saucepan over high heat. Bring to a boil and continue cooking 10 to 15 minutes, stirring occasionally. The rhubarb will break down and should take on a jelly-like consistency.
2. Remove from heat and allow to cool. Add to a blender or food processor. Process until smooth. Cover and place in the refrigerator for 2 hours, or until completely chilled.

To Make the Base:

1. Whisk together heavy cream, milk, sugar, vanilla, and salt in a large bowl. Once sugar is dissolved, cover and refrigerate for 3 hours until chilled.
2. Pour base into ice cream maker. Churn according to manufacturer’s directions.
3. Transfer half of the ice cream to a loaf pan. Spoon half of the sauce over the top. Add the remaining ice cream on top of that, and top again with sauce. Use a knife to swirl.
4. Cover and freeze until firm, 3 hours minimum.