adapted from a recipe in an unknown recipe book
2.5 lbs leeks
3 tbs butter
1.5+ tsp water
8 springs of thyme, leaves removed from stem
Trim off tops (green part) and bottoms (root end) of leeks. Cut the leeks in half lengthwise, then cut them crosswise to make 1/4" half moons. Put into a colander and wash away the grit and sand.
Heat a skillet over med-high heat. Add butter and water (I know, I have never seen this technique either). When butter has melted, add leeks and thyme. Season with salt and pepper. Cook over medium-high heat until leeks are tender, 8-10 minutes. Add a little more water if the leeks start to stick to the bottom of the pan.
Set aside while you make the dough.
2 c flour
1/2 tsp salt
1/4 tsp sugar
6 oz (1.5 sticks) unsalted butter
1/3 c ice water
Combine flour, sugar and salt. Using half of the butter (according to the recipe "should be cool - not cold and hard, but not too soft, either"), cut (mash with back of fork) into the flour mixture until the consistency of cornmeal is reached. Add the other half of the butter in bigger chunks. Work into the dough very briefly, just so it is in the dough, but not homogeneously mixed through. The little butter batches will help make a flaky dough. Lightly fork in ice water until evenly moistened. Divide dough into 2 balls, flatten into a disk, wrap in plastic wrap, and put in the refrigerator for an hour.
About 10 minutes before the dough is done chilling, preheat the oven to 400ºF with a rack in the lowest position.
Roll out one of the disks on a lightly floured surface to make a 12" circle (approx 1/8" thick, if you can tell). Carefully transfer dough circle onto a baking sheet. Lightly flour the dough. I think this is to help absorb some of the liquid from the leeks so it doesn't get soggy. Evenly add the leek mixture to the dough. Only add the leeks in the middle 10" (leave a 1" border). Fold over the border of the dough to make a pseudo-crust. Beat an egg and brush the outside of the dough with the eggwash. This will help in brown in the oven. Put this in the oven for 25-30 minutes.
If the top gets too brown before the bottom does, just place a piece of foil on the top (no need to wrap, just place) and let it finish baking until the bottom browns.
The recipe did not say anything about waiting to cool, so I didn't :)