Heat the oil in an 8-quart saucepot over medium-high heat. Add onions and squash and cook over medium high heat. Add onions and squash and cook over medium heat until they're tender-crisp. Remove the vegetables from the saucepot.
Season the beef as desired. Increase the heat to medium-high. Add the beef to the saucepot and cook until it's well browned on all sides. Remove the beef from the saucepot. Pour off any fat.
Add the broth, orange juice, wine, brown sugar and tomatoes to the saucepot and heat to a boil. Reduce the heat to low. Return the beef to the saucepot. Cover and cook for 2 hours.
Return the vegetables to the saucepot. Cover and cook for 1 hour or until the beef is fork-tender.
Remove the beef to a cutting board. Let stand 10 minutes. Serve the beef with the vegetables and sauce.