How to Make Rhubarb Pie

• Macerate: In a large bowl, combine the rhubarb and strawberries with the granulated sugar. Toss well to coat the fruit, then let it sit for about 1 hour.
• Mix: In a small bowl, whisk together the cornstarch, pectin, and salt until evenly combined. Set this mixture aside.
• Prepare Dough: Roll out one disc of your pie dough into a circle about 14 inches in diameter. Carefully place it into a 9-inch pie plate and cover with plastic wrap. Refrigerate while you prepare the filling.
• Shape Remaining Dough: For a solid-top pie, roll out the second disc and place it on a lined baking sheet. If you prefer a lattice-top pie, roll the remaining dough into a 9- by 15-inch rectangle, cut into strips, and arrange on a lined baking sheet. Cover both with plastic wrap and chill.
• Set Up Ice Bath: Fill a bowl with cold water and ice cubes to create an ice bath.
• Drain Fruit: After macerating, drain the fruit in a colander placed over a large bowl. Retain 6 tablespoons of the liquid for later use, and discard the rest.
• Cook Filling: In a large pot, mix the drained rhubarb and strawberries with the vanilla paste and strawberry jam. Cook over medium heat for about 2 minutes until slightly softened.
• Thicken: Sprinkle the cornstarch mixture over the fruit, stirring until it's evenly coated, about 1 minute.
• Simmer: Stir in the reserved macerating liquid, bring it to a simmer, and cook until thickened, about 2 minutes. Remove from heat and cool in the ice bath for about 30 minutes.
• Preheat Oven: Preheat your oven to 425°F (220°C).
• Assemble Pie: Pour the cooled filling into the prepared pie shell. Place the second crust onto the filling or weave the strips into a lattice.
• Crimp Edges: Fold the edges of both crusts together and crimp them to seal. Make 5 small slits for steam to escape if using a solid top.
• Chill: Place the assembled pie in the freezer for about 15 minutes.
• Brush & Bake: Brush the top crust with the egg wash. Bake at 425°F for 15 minutes, then reduce to 375°F (190°C) and continue baking until bubbly and golden brown, about 45 to 55 minutes.
• Cool: Once baked, remove the pie from the oven and transfer to a cooling rack. Allow it to cool completely before slicing, about 4 hours.