Strawberry Rhubarb Slab Pie

Ingredients

• 4 cups fresh rhubarb cut into ½-inch slices
• 3 cups fresh strawberries, rinsed, hulled and quartered
• zest and juice of one orange
• 1½ cup sugar
• ½ cup brown sugar
• 2 tablespoons cornstarch
• 1 tablespoon cinnamon
• 1 pinch kosher salt
• 1 pinch black pepper
• 2 batches pre-made pie crust (homemade or store-bought), separated
• 1 pinch sanding sugar
• 1 egg, whisked