Rinse the rhubarb stems and cut them into inch long pieces. Place in a medium sized saucepan. Add in those succulent berries.
To the saucepan, add in 1/2 cup rapadura (or sweetener of choice) and the water. Cover and simmer for 5 minutes.
While the rhubarb and berries are simmering, combine the cold butter, flour, oats, freshly grated ginger, and remaining 1/2 cup of rapadura (or sweetener of choice) in a bowl. Use a pastry cutter or your fingers to work the butter through the flour mixture until it resembles a rough crumb texture.
Transfer the simmered rhubarb and berries into a baking dish of choice. Top with the flour mixture.
Bake in a 350 degree oven for 40-45 minutes until warm and bubbly.