Heat oil in a heavy pot over medium-high heat. Brown the beef in batches so it sears, not stews. Remove and set aside.
Lower heat to medium. Sauté onion, garlic, carrots, and celery for about 5 minutes until they start to soften and smell amazing.
Return the beef to the pot. Stir in tomato paste if you’re using it and cook for 1 minute to wake up the flavors.
Pour in beef broth and tomatoes. Add potatoes, thyme, and bay leaf. Season with salt and pepper.
Bring to a simmer, then reduce heat to low. Cover and cook 1.5 to 2 hours, until beef is tender and potatoes are cozy. Stir occasionally.
If you want a thicker sauce, whisk a little cornmeal or flour with a splash of broth, then stir back in. Simmer 5 more minutes.
Taste and adjust seasoning. Remove bay leaf. Serve hot and enjoy the aromatic goodness.