Sweet & Tart Rhubarb Blueberry Pie

Ingredients

• 2 ½ cups all-purpose flour
• 1 tsp salt
• 1 tsp granulated sugar
• 1 cup unsalted butter, chilled and cubed
• 6-8 tbsp ice water
• 2 cups rhubarb, chopped into 1-inch pieces
• 2 cups blueberries (fresh or frozen)
• ¾ cup granulated sugar
• ¼ cup cornstarch
• 1 tsp vanilla extract
• 1 tsp lemon juice
• 1 tsp ground cinnamon (optional)
• 1 egg, beaten (for egg wash)
• Sugar for sprinkling (optional)