Tourtière Québécois Meat Pie

Name: Tourtière (Québécois Meat Pie)
Ingredients: 2½ cups flour; 1 tsp. dry mustard powder; ½ tsp. lemon zest; ½ tsp. kosher salt, plus more to taste; 16 tbsp. unsalted butter, cubed and chilled; Juice of 1 lemon; 1½ cups finely chopped russet potatoes; 2 tbsp. canola oil; 1½ lb. ground pork; 6 cloves garlic, minced; 2 small yellow onions, finely chopped; 1 medium carrot, finely chopped; ½ cup apple cider; ½ tsp. celery seed; ½ tsp. ground cloves; ½ tsp. ground nutmeg; ½ tsp. ground cinnamon; ½ tsp. ground ginger; 2 bay leaves; Freshly ground black pepper, to taste; 1 egg, mixed with 2 tbsp. milk, for egg wash