Sear the beef

• Pat the beef cubes dry and season generously with salt and pepper.
• Heat the olive oil in a Dutch oven over high heat and brown the beef in batches on all sides.
• Set the browned beef aside on a plate.

Build the base

• Lower the heat and cook the onion, carrot and celery in the same pot until softened.
• Add the garlic and tomato paste and cook until fragrant.
• Sprinkle in the flour and stir to coat the vegetables.

Simmer the stew

• Return the beef to the pot with the beef stock and Worcestershire sauce.
• Add the thyme and bay leaves, then bring to a gentle simmer.
• Cover and cook on low until the beef is fork tender, stirring occasionally.

Boil the potatoes

• Place the potatoes in a stockpot and cover with cold salted water.
• Bring to a boil and cook until a knife slides in easily.
• Drain well in a colander.

Mash the potatoes

• Mash the drained potatoes while hot.
• Stir in the butter and warm milk until smooth and creamy.
• Season with salt and pepper to taste.

Serve

• Discard the bay leaves and taste the stew for seasoning.
• Spoon the beef stew over a generous mound of mashed potatoes.