Season the lamb shanks well on all sides with salt and pepper. Next, add some oil to a large pot or rondeau over high heat until it begins to smoke. Place in the lamb shanks and sear them until golden brown on all sides.

Pour in 96 ounces of stock (or enough to where the lamb is at a minimum half submerged), season with salt and pepper, and braise over medium-low heat for 3 hours or until the lamb becomes very tender and falls off the bone. USDA recommends lamb reach an internal temperature of 145F with a 3 minute rest.

In the meantime, prepare the barley and set it aside.

Next, prepare the split peas and set them aside as well.

Add some oil to a separate large pot over medium heat and cook the leeks and onions until browned, which takes about 20 minutes. Stir in the garlic and cook just until fragrant, which usually takes about 1 minute. Add in the vegetables and sauté for 5 to 6 minutes over low heat to medium heat.

Remove the lamb shanks and chop into small pieces. This should be very easy since it will be so tender.

Add the lamb along with the braising liquid to the pot of vegetables. Add additional stock until your desired consistency.

Cook over low to medium heat until the vegetables are tender, which takes about 25 minutes.

Season the soup with salt and pepper and stir in the chopped parsley.

Serve the soup by adding it to a serving bowl and spoon in the desired amount of barley and split peas.