Combine the almond flour, tapioca flour, coconut sugar, salt and butter in a food processor, or use a pastry blender in a bowl. Pulse or blend until the texture of coarse meal.

In a small bowl, whisk the egg and then add to the dry ingredients. Pulse/mix again until dough comes together. If you’re mixing in a bowl, you may want to use your hands to bring the dough together at the end.

Divide the dough into two equal pieces and form into flat, round discs. Wrap each dough disc in plastic wrap. Refrigerate for at least 1 hour or up to overnight.

When you’re ready to bake, preheat oven to 425°F.

Roll out one round of dough in between two sheets of parchment or on a silicone baking mat into a 12-inch circle. Carefully lay dough into a 9-inch pie dish (not deep dish). If the dough breaks, that’s okay! Just press it back into place and repair any holes/cracks that may have formed. Place in the freezer while preparing the filling.

Mix together the rhubarb, strawberries, coconut sugar, tapioca starch, zest and juice of lemon, cinnamon, nutmeg, allspice, salt, and vanilla. Mix well in a large bowl and pour out into chilled crust.

Roll out the second round of dough in between two sheets of parchment or on a silicone baking mat into a 12-inch circle. Use a pizza cutter or sharp knife to cut into even 3/4” strips (you can also make them wider, depending on what sort of look you want). At this point, I recommend putting the cut strips back into the refrigerator about 10 minutes to firm back up - it will make them easier to work with and reduce breakage. Use your chilled dough strips to cover the pie with a lattice work crust - I used the method depicted here. Be extra careful when folding the strips - the lack of gluten in the crust makes the dough much more susceptible to breaking, but if it does, just press the strips back into place. Mine broke a fair bit but you can’t tell once it’s baked!

Using a silicone pastry brush, brush the crust with the egg white beaten with water.

Place the pie on a baking sheet and bake 15 minutes at 425°F. Reduce the temperature to 350°F, and continue baking for 50-60 minutes or until the pie is the pie is golden brown on top and the filling is bubbling. Tent with foil if the pie starts to brown too quickly!

Let cool for at least 1 hour before serving. Serve warm or chilled. Keep any leftovers stored in the refrigerator.