Leek tarte tatin

1. Prepare the Ingredients:
- Preheat your oven to 200°C (390°F).
- Trim the leeks, removing the dark green tops and roots. Cut the leeks lengthwise and then into 2-inch pieces.
- Roll out the puff pastry on a lightly floured surface to fit the size of your oven-proof skillet and set it aside.

2. Cook the Leeks:
- In a medium oven-proof skillet, melt the butter over medium heat.
- Add the brown sugar and cook, stirring continuously, until the sugar dissolves and starts to caramelize, about 2-3 minutes.
- Stir in the vinegar and mix well.
- Add the leeks, cut side down, into the caramel mixture carefully. Let them cook for about 5-10 minutes until they start to soften and become caramelized, turning them occasionally to ensure even cooking.
- Season with salt and pepper to taste.

3. Assemble the Tarte Tatin:
- Carefully place the rolled-out puff pastry over the caramelized leeks in the skillet.
- Tuck the edges of the pastry down around the leeks to encase them.
- Make a few small cuts on the pastry to allow steam to escape during baking.

4. Bake:
- Place the skillet in the preheated oven.
- Bake for 25-30 minutes, or until the puff pastry is golden brown and fully cooked.

5. Serve:
- Once baked, remove the skillet from the oven and let it cool slightly, about 5 minutes.
- Place a large plate over the skillet and carefully invert the tarte tatin onto the plate so the caramelized leeks are on top.
- Drizzle the tarte tatin with lemon juice.
- Spoon dollops of sour cream over the top.
- Garnish with fresh basil leaves.

6. Enjoy:
- Serve your leek tarte tatin warm as an appetizer, side dish, or light main course.