Place the salt, pepper, onions, garlic and scallions in a food processor and puree.
To create the cavity for the stuffing, use a long sharp knife and make a hole through the center of the roast making a lengthwise slit and taking some of the meat from the center out and reserve it for the filling.
Turn the meat around and cut another slit in the same spot so that your knife completes the cavity. Rub half of the onion mixture and place the beef in a bag and refrigerate overnight.
Stuff the beef with the meat, carrots, eggs and half of the onion mixture, pushing with your fingers to be sure the filling goes all the way through. Tie the end of the beef so the filling does not come out.
Take the beef from the fridge and let it rest for 30 minutes. Wrap it with plastic wrap and foil, place it in a pot and cover with water and salt.
Cover and cook over medium heat for about 3 hours. Add more water or beef broth if necessary.