In a medium saucepan, combine rhubarb and sugar.
Stew over medium until rhubarb is tender.
Puree the sliced strawberries, rhubarb and banana in a blender until smooth. Strain.
In a small bowl, mix gelatin with orange juice. Stir to dissolve, and let soften for 5 minutes.
Warm gelatin over low heat. Stir into rhubarb-strawberry puree.
Add sugar, and stir to dissolve.
Freeze in ice cream maker. Scoop sherbet into bowls.
Top with strawberries.