1. Whisk the flour and salt together in a large bowl. Cut in the cold butter until the pieces are pea-sized.

2. Stir in the sour cream until a shaggy dough forms. Press the dough into a disk, wrap it, and refrigerate for at least 4 hours or overnight.

3. For the filling, combine the diced apples, brown sugar, cinnamon, flour, and lemon juice in a saucepan. Cook for 5 to 7 minutes, until the apples soften slightly and the mixture thickens. Let it cool.

4. Preheat the oven to 375°F. Line a baking sheet with parchment paper.

5. Divide the chilled dough in half. On a lightly floured surface, roll each half into a rectangle about 14 x 6 inches.

6. Spoon half the filling in a strip down the center of each rectangle, leaving a border of about 2 inches on each long side.

7. Fold the long sides over the filling so they meet in the middle, then pinch the seam and the ends firmly to seal.

8. Carefully move each kringle to the baking sheet, seam side down. Cut a few small slits in the top to let steam escape.

9. Bake for 25 to 30 minutes, until golden brown.

10. Let the kringles cool for about 15 minutes. Whisk the powdered sugar, milk, and vanilla into a smooth glaze and drizzle it over the kringles.