Trim the bottom of the leeks, make a lengthwise slit to the center, and separate them into leaf-like layers. Place a spoonful of the filling at one end of each leek, fold it into a triangular shape, and continue folding along the length of the leek until it resembles a pastry.
Arrange the triangles in a baking dish. Mix all the sauce ingredients and pour them over the triangles. Cover with damp parchment paper and aluminum foil, then bake for an hour and fifteen minutes.
Remove the cover (if the liquids have evaporated, add 1/2 cup of water) and bake uncovered for an additional 15 minutes.
RECIPE NOTES
You can arrange the leeks in a flat pot, add an extra cup of water to the sauce, and simmer on low heat until they become tender.
You can also roll the leek leaves into thin rolls.
For a vegetarian option, replace the meat with chopped mushrooms sautéed with a bit of onion.