Preheat oven to 350 degrees Fahrenheit. Season all sides of the short ribs with salt and pepper.
Heat a heavy, oven-safe pot (with lid, for later use) over high heat. Add in olive oil and allow to heat briefly. Sear short ribs in olive oil, about 1 minute per side, to render fat. Remove from pot and set aside.
Add in onion and saute 3 to 5 minutes, until softened. Add in garlic and saute 1 minute more.
Pour in beef broth, red wine (if using) and Worcestershire sauce. Bring to a simmer. Return short ribs to pan. Place a rosemary sprig on top.
Cover with lid and transfer to preheated oven to braise for about 2.5 hours, until meat is tender and easily shredded with a fork. Be sure the lid is sitting properly to avoid having your liquids evaporate through steam escaping the pot.
Discard rosemary and serve hot with additional salt and pepper, to taste.
