Season the beef with salt and pepper. Heat olive oil in a heavy pot over medium-high heat. Brown the beef in batches until it’s nicely seared on all sides. Don’t overcrowd the pan—we’re going for flavor, not a soggy mess.
Set browned meat aside. In the same pot, add the onion and a pinch of salt. Sauté until translucent, 3–4 minutes. Add garlic and cook for 30 seconds more, until fragrant.
Stir in tomato paste if using, then pour in beef broth and water. Scrape up all the flavorful bits from the bottom. Return the beef to the pot.
Add carrots, potatoes, thyme, rosemary, and bay leaves. Bring to a gentle simmer, then cover and cook for about 1.5 to 2 hours, until beef is tender and the flavors have mingled like old friends.
Taste and adjust salt and pepper. If you want a thicker stew, whisk the cornstarch slurry into the pot and simmer 3–5 minutes until thickened