Pat beef chunks dry with paper towels and season lightly with salt and pepper.

Chop the onion, slice the carrots, dice the potatoes, and mince the garlic. Keep vegetables roughly the same size so they cook evenly.

Heat 2 tablespoons olive oil in a large heavy-bottomed pot or Dutch oven over medium-high heat.

Add beef in batches to avoid crowding. Brown all sides — about 3–4 minutes per batch. Transfer browned beef to a plate.

Reduce heat to medium. Add the chopped onion and cook until softened, 4–5 minutes. Stir in garlic and cook for 30 seconds.

Stir in 2 tablespoons tomato paste and cook for 1–2 minutes to remove raw flavor.

Pour in 4 cups beef broth and 1 cup stout beer if using. Scrape up any browned bits from the bottom of the pot.

Return the beef to the pot. Add 1 teaspoon thyme and 1 teaspoon rosemary. Bring to a low simmer.

Cover partially and simmer gently for about 1½ to 2 hours, until the beef is fork-tender.

Add sliced carrots and diced potatoes. Continue simmering until the vegetables are tender, about 20–30 minutes.

Taste and adjust seasoning with salt and pepper. For a thicker stew, mash a few potato pieces into the broth or mix 1–2 teaspoons cornstarch with cold water and stir in.

Remove from heat and let rest a few minutes before serving.