Cut beef into 1-inch cubes or purchase already cubed. Season the cubes with salt and freshly ground black pepper. Heat oil in a Dutch oven or large pot over medium heat until hot. Brown beef in batches. Return cooked beef and accumulated juices to Dutch oven.
Stir in tomatoes, broth, garlic, salsa, chili powder and oregano. Bring to a boil; reduce heat to low. Cover tightly and simmer 1½ to 1¾ hours, until beef is tender.
Serve with sour cream and green onions, if desired.