Toss the beef chunks in oil, salt, pepper, and plain flour. The flour helps the meat crisp up when browned.
Place the meat into a hot pan and brown it on all sides. Remove once browned.
In the same pan, add chopped onion, carrots, and leek. Turn the heat down and let them sauté slowly until soft.
Stir in tomato purée, garlic powder, paprika, and thyme. Let it cook for a few minutes until the mixture thickens slightly.
Pour in the beef stock, half a tin of Guinness, and a splash of Coca-Cola. Stir to combine.
Add the browned meat back in, cover with a lid, and simmer on low heat for 4 hours.
Remove the lid and check the consistency. The stew should be thick and rich with a balanced flavour.
Serve with mashed potatoes, crusty bread, or eat straight from the pot.