The Delicious Crescent

Stove Top
2 Heat one tablespoon of oil in a cast iron skillet over medium high heat.
3 When the oil is hot, place the lamb shanks and season well with salt and pepper. You may work with two shanks at a time.
4 Then brown the shanks well on all sides using a pair of tongs. It should take about 6 to 8 minutes. Transfer the seared lamb shanks and set aside.
5 In the same skillet add the remaining oil and heat it. Then add the sliced onion and sauté until light golden brown.
6 Next add the grated garlic and stir couple minutes. Add the Persian spice mix, and turmeric. Then turn of the heat.
7 Transfer the lamb shanks and sautéed onion-spice mixture to a heavy bottomed cooking pot. Add the saffron water, lemon juice, bay leaves, thyme (or dill) and the lemon zest.
8 Add about 2 cups of water and bring it to a boil, and then lower the heat and let it simmer for about 1½ to 2 hours until fork tender. The meat should be falling of the bone.
9 Adjust the seasonings as per taste.
10 Transfer the lamb shanks to a serving dish.
11 Cook down the sauce further if it is too thin and then pour it over the lamb shanks. Or you may strain the sauce and then cook it. Discard the bay leaves.
12 Tip: You may also cook this from start to finish in a dutch oven or a heavy bottomed pot that heats up well for browning the meat.
Oven:
15 Follow the same instructions as above.And cook the lamb shanks in the oven at 325 degrees F in an oven safe dish making sure to seal it well or use a fitting lid.
Slow cooker:
18 Brown the lambs shanks and prepare the onion-spice-herb mixture. Transfer to slow cooker. 
19 Add the water and cook according to the instructions for about 4 to 5 hours at high or 6 to 8 hours at low setting.