01 - Preheat oven to 320°F or set slow cooker to low heat setting.
02 - Generously season lamb shanks with salt and black pepper.
03 - Heat olive oil in a large Dutch oven or heavy ovenproof pot over medium-high heat. Sear lamb shanks on all sides until evenly browned, about 8 minutes total. Remove and set aside.
04 - Add onions, carrots, and celery to the same pot. Cook, stirring occasionally, until softened, about 5 to 7 minutes. Add garlic and sauté for an additional minute.
05 - Stir in tomato paste and cook for 1 minute. Pour in red wine and scrape the pot’s bottom to loosen browned bits. Simmer for 2 minutes to reduce slightly.
06 - Stir in crushed tomatoes, stock, rosemary, thyme, bay leaves, and oregano. Mix thoroughly to combine.
07 - Nestle lamb shanks back into the sauce. Bring mixture to a gentle simmer.
08 - Cover tightly and transfer to oven or slow cooker. Cook until meat is tender and falling off the bone—approximately 2.5 to 3 hours in the oven or 7 to 8 hours on low in a slow cooker.
09 - Remove lamb shanks and cover with foil to keep warm. Skim excess fat from sauce. Optionally simmer uncovered on stovetop for 10–15 minutes to thicken.
10 - Plate lamb shanks and spoon sauce generously over. Garnish with fresh herbs if desired.