Cook tongue: Rinse the tongue well with water and place in a large pot. Add water, the scallions, salt and pepper.
Cover pot and bring to a boil. Simmer, partially covered, until tongue is tender, 2 ½ to 3 hours.
Transfer tongue to a cutting board and, when cool enough to handle, peel off the skin and trim any fat or gristle. Set aside.
Make the creole sauce: Heat the oil in a large saucepan. Add the onions, tomatoes, garlic, scallions,ground cumin and cook gently for 10 minutes, stirring until softened.
Reduce the heat to low, add the salt and cook for 10 minutes more, stirring occasionally until the sauce has thickened. Check and adjust the seasoning. Slice tongue and add it to the sauce with the beef broth and continue cooking for about 10 minutes more.
Notes
If you own a pressure cooker, you can cook the tongue faster.
If you cook it on the stove be sure the heat is low and cook it for about 3 hours or until is soft and done. If you don't cook it long enough it will be hard.