Pat lamb shoulder chunks dry with paper towels and season generously with salt and freshly ground black pepper.

Heat vegetable oil or rendered lamb fat in a large heavy-bottomed pot or Dutch oven over medium-high heat. Brown lamb in batches for 4-5 minutes per batch until all sides are seared. Remove lamb and set aside.

Lower heat to medium. Add chopped onion and minced garlic to the pot and cook until softened and fragrant, about 5 minutes, stirring often.

Return lamb to the pot. Pour in beef or lamb stock to just cover the meat. Add fresh thyme sprigs and bay leaves. Bring to a gentle boil, then reduce heat to low and simmer covered for 1 hour, stirring occasionally.

Add chopped carrots, parsnips, and potatoes to the pot. Stir gently, cover, and simmer for another 30-40 minutes until vegetables are tender but not mushy.

Taste and adjust seasoning with salt and pepper. Remove thyme sprigs and bay leaves. Stir in chopped fresh parsley.

Ladle stew into warm bowls and serve with crusty bread or buttered soda bread.