01 - Heat the oven to 320°F.
02 - Pat lamb pieces dry and season generously with salt and pepper.
03 - Warm olive oil in a large Dutch oven over medium-high heat. Sear lamb in batches until browned on all sides, then remove and set aside.
04 - Add onion, carrots, and celery to the pot and cook for 5 to 7 minutes until softened. Stir in garlic and cook for an additional minute.
05 - Stir in tomato paste and cook for one minute. Pour in red wine, scraping the bottom to lift caramelized bits.
06 - Return lamb to the pot. Add stock, rosemary, thyme, and bay leaves. Bring mixture to a gentle simmer.
07 - Cover and place pot in the oven. Cook for 2 to 2 1/2 hours until lamb is tender and easily pulled apart with a fork.
08 - Remove from oven, skim excess fat. Optionally, stir in butter for added richness. Discard herb stems and bay leaves, adjust seasoning, and serve hot garnished with fresh herbs.