Directions

1. 1. Put the oil in a large deep skillet or flameproof casserole with a lid and turn the heat to medium-high.
2. 2. Add the lamb, sprinkling the meat with salt and pepper as it browns.
3. 3. When the pieces are deeply browned, after at least 10 minutes, transfer to a plate, pour or spoon off any excess fat.
4. 4. Add the vegetables and the oregano, along with some more salt and pepper, and cook, stirring occasionally, until the onions soften, 5 to 10 minutes.
5. 5. If you are using shanks, remove the vegetables with a slotted spoon and set aside.
6. 6. Add the wine and let the mixture bubble for about a minute.
7. 7. Remove about 1/2 cup of dill leaves and reserve, tie the dill stems with the remaining attached leaves into a bundle and add to the pot along with the stock. Return the lamb to the pot and cover. Adjust the heat so the mixture simmers steadily but not violently.
8. 8. If you're using lamb shanks, return the vegetables to the pot when they are nearly tender, an hour or more later.
9. 9. In any case, cook until the lamb is tender. (You can prepare the dish to this point and let sit for a few hours or cover and refrigerate for up to a day before reheating and proceeding.)
10. 10. When the lamb is nearly done, make the Avgole-mono.
11. 11. Turn the heat to low, then stir the sauce into the lamb and heat through; do not boil.
12. 12. Taste and adjust the seasoning and serve in bowls, garnished with the reserved dill.