Place a bowl and whipper for the whipped cream in the freezer to chill.
In a small pot add the rhubarb and sugar. Cook for about 10 min. simmering or until rhubarb falls apart and is very soft. Set aside to cool completely.
When rhubarb is cooled, in a large bowl, whisk together the condensed milk, vanilla, and salt. Add the rhubarb.
Whip the cream using the cooled equipment on high speed until stiff peaks form. Fold one cup of the whipped cream in the condensed milk mixture and combine well. Fold in the rest until well combined.
Place in a 9x5x3" pan, it will be very full or use more than one container. Cover lightly and freeze.