In a kettle over medium-low heat, cook and stir rhubarb, water and sugar until rhubarb is soft and tender. Remove from the heat; stir in gelatin until dissolved. Stir in orange juice and zest. Chill until partially set, about 2-3 hours. Stir in strawberries. Pour into six 5-cup ring molds coated with cooking spray. Refrigerate overnight. Unmold onto lettuce-line platters; garnish with berries.
For dressing, combine mayonnaise and whipped topping; add enough milk to thin to desired consistency. Serve in a bowl in center of mold.