Gluten-Free Strawberry Rhubarb Crumble Pie

gluten-free pie crust: recipe and instructions are in the recipe card below. This buttery pie crust is made with almond flour. If you don't need this pie to be gluten-free, use your favourite pie crust recipe or use my never-fail pastry recipe made with all-purpose flour that you'll find in this recipe for Lemon Tart with Blueberries.

strawberries: Fresh strawberries make the best pie filling! I haven't tried this recipe with frozen strawberries. If you do, make sure they are very well-drained to avoid ending up with a soggy pie.

fresh rhubarb: The same advice applies. If you're using frozen rhubarb, pat it dry first to absorb excess moisture.

sweetener: You can use granulated sugar or coconut sugar or Lacanto Monkfruit sweetener with erythritol to keep this pie filling sugar-free. I've tested this recipe with both sugar and Monkfruit sweetener.

cornstarch: Use your choice of cornstarch, arrowroot powder or instant tapioca to thicken the filling.

orange zest: Fresh orange zest adds a hint of another layer of flavour!

orange juice: just a tablespoon of freshly squeezed orange juice.

vanilla: pure vanilla extract

For the crumble topping: rolled oats, almond flour (or oat flour), butter, and sweetener (choices as above.)

You'll need to make the pastry for the pie ahead of time, as it needs to be wrapped in plastic wrap and chilled in the fridge for a few hours, or even overnight.

You'll find complete instructions for making the pastry in the recipe card below. It's a snap when you use a food processor, but you can also combine the ingredients in a medium bowl and cut in the cold butter with a pastry cutter.

Once you're ready to bake the pie, roll the dough on a pastry mat or sheet of parchment paper. You will likely need a little extra tapioca flour to sprinkle on the dough to make it easier to work with.

To make transferring the rolled dough to the pie plate easier, invert the pie plate over the rolled-out dough. Carefully lift and flip the parchment paper (or pastry mat) with the dough and the inverted pie plate. The pastry will probably tear, but that's okay. It's easy to fix.

Remove the parchment paper or pastry mat. Gently press the dough into place in the baking dish, pinching any tears together with your fingers. Form a fluted edge on your pie shell, or crimp the edges with your fingers if desired.

Store the crust in the refrigerator while you prepare the filling. There's no need to bake it first.

If you find there is liquid at the bottom of the bowl of fruit, leave it behind and just spoon the fruit into the pie crust. Sometimes strawberry rhubarb pie can be a bit of a watery mess if the berries are particularly juicy.

You'll notice I used a full ¼ cup of cornstarch to thicken the filling. If you'd like, you can use instant tapioca as a thickener, instead of cornstarch. Use the same amount. For more information on thickening with tapioca, see this article, How to Use Tapioca for Pies.

Next, prepare the crumble topping. Soften the butter and combine it with rolled oats, almond flour and sweetener, using a fork or even your fingers to make a crumbly mixture.

And finally, gently press the crumble topping over all, cover the edges of the crust with a pie shield or a strip of aluminum foil and bake until deep golden brown.