Grandma Joans Butter Tarts

Name: Grandma Joan's Butter Tarts
Ingredients: For the Crust; 3 3/4 cups all-purpose flour; 3 tablespoons granulated sugar; 1/2 teaspoon kosher salt; 2/3 cup unsalted butter, COLD (NOT room temperature), cut into pieces; 2/3 cup shortening, COLD (NOT room temperature); 2/3 cup ice water; 3 teaspoons distilled white vinegar; For the Butter Tarts; 1 1/2 cups dark brown sugar; 1/2 cup dark corn syrup; 1/4 cup unsalted butter, melted and slightly cooled; 2 teaspoons vanilla extract; 1/2 cup raisins or currants; sea salt, for sprinkling (optional)