Lightly grease or spray a large casserole dish. Set aside.
Place 1 tablespoon olive oil and 1 tablespoon butter into a pan. Place pan over a medium heat and heat until butter is melted and hot.
Add beef to the pan in batches. Cook, stirring and tossing, until browned.
Remove beef from pan and place in prepared casserole dish. Season lightly, to taste, with salt and pepper. Toss to coat well.
Using the same pan, add remaining 1 tablespoon olive oil and 1 tablespoon butter. Place pan over a medium heat and heat until butter is melted and hot.
Add onion, garlic, carrots, celery, parsnip and thyme and cook. Cook, stirring, for 3 to 5 minutes, until onions are fragrant. Season well, to taste, with salt and pepper.
Add Irish Stout. Simmer for 5 minutes.
Add beef stock, Worcestershire sauce and tomato paste. Simmer for 30 minutes. Liquid should reduce by at least 1/3.
Season with salt and pepper, to taste.
Serve hot with bread.