- In a large Dutch oven or pot, heat the 2 tablespoons of olive oil or medium-high heat. Pat dry the lamb shanks with paper towels and season generously with Kosher salt and black pepper on all sides.
- Preheat the oven to 350 degrees F.
- Once the oil is hot, add in the lamb shanks and cook for about 3 minutes per side, until browned. Transfer them to a plate and set aside.
- Carefully drain all but about 1-2 tablespoons of drippings from the pot.
- Add the onion, carrots and celery to the pot and stir until slightly softened about 5 minutes. Add the garlic to the pot and cook for 2 minutes while stirring.
- Next, add in the tomato paste and allow this to brown for about 3 minutes. Deglaze the pan with the red wine and carefully scrape up any browned bits from the bottom of the pot. Let it simmer for 5 minutes.
- Add the lamb shanks back to the pot along with the broth, tomato sauce, herbs and bay leaves. Stir to combine and bring it to a simmer.
- Cover the pot, transfer it to the lower part of the oven and cook for 2 hours. Uncover and cook for another 30 minutes to reduce the sauce.
- Remove from the oven and discard the bay leaves and thyme. Adjust the sauce to taste with more salt and pepper as needed.
- Serve over mashed sweet potatoes with extra sauce.
NOTE: If the sauce is too thin, make a cornstarch slurry by mixing 1-2 tablespoons of cornstarch into 3-5 tablespoons of cold water. Whisk into the sauce to thicken.