Pat the roast dry with paper towels. Use the tip of a sharp knife to make 8 small incisions around the roast. Put a sliver of garlic into each cut. Season on all sides with salt and pepper.
In a pot, heat 3 tablespoons oil over high heat. Brown the roast in the pot, several minutes on each side. Once it is nicely browned all over, remove it from the pot. Wipe the pot clean with a paper towel.
Heat 2 tablespoons oil in the pot over medium heat. Add half of the sliced onions and saute for 4-5 minutes. Set the roast on top of the onions. Add the carrots, celeries, bay leaves, and remaining onions.
Add the beef broth, Worcester sauce, turmeric, saffron and cinnamon.
Cover the pot and bring to simmer. Then adjust the heat down to the low heat so the liquid is simmering, not boiling. Cook with the lid on until meat is very tender, about 7-8 hours or longer.
Let roast stand for about 15-20 minutes, then slice to desired thickness or shred it into big chunks using two forks.