Sour Cream-Sweet Potato Pie

Name: Sour Cream-Sweet Potato Pie
Prep time: 30 min
Total time: 30 min
Cuisine: American, Southern
Ingredients: 1 1/4 c. all-purpose flour; 1 tbsp. sugar; 1/4 tsp. salt; 1/2 stick cold unsalted butter, cut into 1/2-inch pieces; plus 3 tablespoons; 4 tbsp. cold lard, cut into 1/2-inch pieces; 1 c. light-brown sugar; 2 tbsp. all-purpose flour; 1/2 tsp. ground cinnamon; 1/4 tsp. grated nutmeg; 1/2 c. milk; 1/2 c. sour cream; 3 large eggs, plus 1 large yolk; 1 tsp. pure vanilla extract; 2 c. puréed cooked sweet potatoes (from about 1 1/2 pounds)