In a large pot, add 1-1/2 cups of water, then the rhubarb, sugars and salt. Cook over medium heat, stirring and mashing, while it cooks.
Pour this mixture through a strainer into a bowl , push it through a strainer with a spoon.
Use all that you can push through.
Mix and transfer to a shallow pan and freeze,for 4 hours. Each hour mix and mash in the pan, then back into the freezer.
Spoon into bowls, top with a couple fresh strawberries.