In the same pan, sauté the onion. Add butter, if needed. Add the garlic and cook for 1 minute. Return the meat to the pan and add the port wine. Bring to a boil and simmer gently for about 5 minutes. Add the broth and dates. Bring to a boil. Cover and simmer gently for about 1 hour and 30 minutes or until the meat is tender. Season with salt and pepper.