Add the onion, celery, rosemary (tie string around it doesn't leave needles all through the stew), thyme, oregano, and bay leaves. If needed, add a couple tablespoons of water to break up the fond and cook the onions until translucent. Add the meat back in, along with the diced tomatoes and 3 cups beef stock. Bring to a simmer, cover and place in the oven for 2 hours.