Season roast heavily with salt and pepper. Heat oil in a dutch oven. Sear roast for a couple minutes on each side over medium-high heat. The roast should be nicely browned on all sides. Transfer roast to large plate.
Add onion and garlic to the pot, stirring over medium heat until onions are soft. Stir in flour and tomato paste followed by broth, water and Worcestershire sauce. Stir and scrape seared bits from bottom of pot. Add roast back to pot, cover tightly and place in oven. (Optional: use a slow cooker instead of the oven. Sear beef in heavy bottom sauté pan, follow instructions above then transfer to slow cooker, low for 6 to 7 hours until tender.).
Cook for 2 hours, turn roast, add rosemary and cook approximately one more hour, until completely tender.
Transfer roast to cutting board and tent with foil. Remove rosemary and, using a ladle, skim fat from liquid. Place dutch oven on stovetop and bring to a boil.
Slice roast against the grain or pull in bite-size pieces. Serve with reduced sauce.