Preheat large Dutch oven on medium-high heat and add 1 tablespoon of olive oil. Season lamb with 1/2 teaspoon salt and 1/2 teaspoon ground black pepper. Add half of the lamb to the pot and cook until golden brown, for about 7 minutes and stirring just a few times. Transfer to a large plate and repeat with remaining lamb.

Add remaining 1 tablespoon of olive oil and add onion, celery and garlic. Saute until translucent, stirring occasionally. Then add oregano and thyme, and saute for another 30 seconds, stirring constantly. Add tomato paste and stir with vegetables until incorporated. Add mushrooms.

Add beef broth, red wine, Worcestershire sauce, bay leaves, remaining 1/2 teaspoon salt and 1/2 teaspoon black pepper, previously browned lamb and stir.

Cover pot with a lid and bring to a boil. Then reduce heat to low and simmer for 1.5 hours or until lamb is fork tender.

Add potatoes and carrots, stir and simmer for 25 minutes or until potatoes are fork tender.

Turn off heat and let lamb stew stand in a pot covered for about 10 minutes. Serve hot, garnished with parsley if you wish, and a slice of Irish soda bread.