Arrange the flank steak in a large pot so it’s not folded. Add the broth. Bring to a boil and simmer for 15 minutes.
Turn the steaks and cook (simmering) another 30-35 minutes, turning again about halfway through the cooking time.
Remove the steak from the pot and let it cool. Use two forks to shred it into strings. Add it back to the broth while you make the red sauce.
Heat the oil in a pot or large, deep skillet over medium heat. Add the onions. Cook gently for 5 min. stirring frequently.
Next, add the garlic, salt, oregano, cumin, and black pepper to the skillet and cook for 1 minute, stirring frequently.
Add the white wine and cook for 1-2 minutes until most of the liquid evaporates.
Add the tomato sauce and the bay leaf to the pot and bring the sauce to a simmer.
Lower the heat, cover, and cook for 15 minutes. Keep it at a gentle simmer.
Add the shredded steak (along with any broth remaining in the pot) to the tomato sauce.
Stir well to combine. Cover and cook for 10-15 minutes, to let the flavors come together.
Remove the bay leaf and discard. Taste and add salt, if needed.
Serve with white rice, black beans and plantains.