• Preheat the oven to 350°F and lightly butter the baking dish. For this recipe I used a 10-inch round ceramic baking dish.

Make the Crumble Topping

• Cut the cold butter into 1/2-inch cubes and place it back in the refrigerator so it stays cold while you prepare the other ingredients.
• Place the flour, brown sugar, cinnamon, ginger, and salt in a medium size bowl. Whisk until well combined. Add the butter to the dry ingredients and toss the butter into the flour mixture with your hands until all the butter is well coated.
• Use the pastry blender to cut the butter into the flour mixture, until the butter is pea sized. You can also you use your hands if you don’t have a pastry blender. To mix it with your hands take each piece of butter and smash it flat between your index finger and thumb. Continue to do this until the butter is pea sized.
• Place the crumble in the refrigerator to keep it cold until ready to use. The crumble can be made up to one week in advance.

Make the Rhubarb Filling

• Whisk together the tapioca, sugar, and salt in a small bowl and set aside.
• Wash the rhubarb and dry them with a paper towel. Cut the stalks into 1/2-inch pieces.
• Place the rhubarb in a bowl. Zest the orange directly onto the rhubarb. Juice the orange and add 2 tablespoons of orange juice to the rhubarb. Use a silicone spatula to toss the ingredients together. Sprinkle the tapioca-sugar mixture over the rhubarb and fold the dry ingredients into the rhubarb until there are no white flecks left. Let the rhubarb mixture sit for 5 minutes and then taste them. If the rhubarb is too tart add 2 more tablespoons of sugar and taste again.
• Let the rhubarb sit for another 5 minutes to let the sugar and tapioca finish dissolving. Spoon the rhubarb filling into the prepared baking dish and use the back of the spoon to make an even layer. Spread the crumble over the fruit by taking a small handful of the crumble, squeezing it together then breaking it into small chunks over the rhubarb filling. Leave the edges of the filling exposed so you can see the rhubarb juices bubbling up as they crumble bakes.

Bake the Rhubarb Crumble

• Bake the rhubarb crumble for 25-30 minutes until you see the rhubarb juices bubbling up all the way around the baking dish and some of the crumble has started to brown on top.
• Remove the crumble from the oven, set it on a wire rack to cool for 30 minutes to allow the juices to set up. It will still be warm.
• Serve it plain, or with vanilla ice cream with some of the juices from the pan spooned over the top.

Storage

• The crumble can be stored at room temperature for 1 day unless it is very warm in your house (over 75 degrees F). In that case I recommend storing it in the refrigerator at the end of day covered with plastic wrap. The crumble is good in the refrigerator for up to 4 days.