Anna Olson's Blueberry Lattice Top Pie

Ingredients

• 4 cups fresh blueberries
• 1 medium apple (peeled and coarsely grated)
• 1 cup granulated sugar
• 1 tbsp lemon or lime juice
• 1 tsp lemon or lime zest
• 1/4 tsp ground cinnamon
• 2 1/2 tbsp cornstarch
• pie dough (shaped into two discs & chilled)
• 1 egg (mixed with 2 tbsp water)
• granulated sugar (for sprinkling)
• 2 1/2 cups all-purpose flour
• 1 tbsp granulated sugar
• 1 tsp salt
• 3 tbsp vegetable oil
• 2 cup cool unsalted butter (cut into pieces)
• 1/4 cup cool water
• 2 tsp white vinegar or lemon juice