Combine the coconut sugar and arrowroot powder in a small bowl. Spread the rhubarb in a greased 9x13 baking dish and sprinkle with the sugar mixture.
Zest and juice the two oranges directly over the dish and stir to combine.
Cook the rhubarb mixture for 45 minutes, stirring once, until rhubarb is tender.
Remove from the oven and allow to cool until the juices have thickened.
Add the strawberries to the cooled rhubarb mixture, adding the water 1 tbsp at a time, stirring to combine.