Preheat oven to 350 degrees F. Grease an 8x8 or 9x9 pan and set aside.
In a medium bowl, stir together the rhubarb, strawberries, 1/2 cup of the sugar, orange juice, and cornstarch. Transfer into the greased pan.
To make the topping: Combine the other 1/2 cup of sugar, brown sugar, flour, salt, and rolled oats. Cut in the solid coconut oil until the oil has broken down into pea sized pieces. Sprinkle over the top of the fruit filling and bake for 1 hour. Serve warm topped with ice cream!