Instructions:

1. Make the Dough: In a large bowl, mix the flour, salt, and sugar. Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs. Gradually add ice water, mixing just until the dough comes together. Divide into two discs, wrap in plastic wrap, and chill for at least 1 hour.

2. Prepare the Filling: In a large bowl, toss rhubarb and apples with lemon juice. In another bowl, combine granulated sugar, brown sugar, cornstarch, cinnamon, nutmeg, and salt. Mix everything together and let sit for 20–30 minutes to draw out excess juice.

3. Assemble the Pie: Preheat oven to 400°F (200°C). Roll out one disc of dough and fit it into a 9-inch pie plate. Spoon in the filling and dot with a few small pieces of butter if desired. Roll out the second crust, then either lay it flat with slits or create a lattice top. Seal and crimp the edges. Brush with egg wash and sprinkle with raw sugar.

4. Bake the Pie: Bake at 400°F for 20 minutes. Then reduce temperature to 350°F (175°C) and bake for another 35–40 minutes, until the crust is golden and the filling is bubbling. Tent with foil if the crust edges brown too quickly.

5. Cool and Serve: Allow the pie to cool at room temperature for at least 3 hours to fully set before slicing