Arrange the flank steak in a large pot so that it’s not folded or overlapping. Add the beef broth. Set the pot over high heat. When the broth comes to a boil, lower the heat to medium and cook for 15 minutes.
Turn the meat, lower the heat to medium-low and cook 30-35 minutes. Turn the flank steak again about halfway through the cooking time. Keep the broth at a simmer, if it’s boiling too vigorously lower the heat a bit.
Remove the meat from the pot and place it on a cutting board or pan to cool. Keep the broth barely at a simmer over low heat.
When the steak is cool enough to handle, shred it to resemble thin strings. Add the meat back to the broth. Keep on low heat until the tomato sauce is ready.
Make the tomato sauce
Heat the olive oil in a large, deep skillet over medium heat. When the oil is hot, add the onions. Cook for 5 minutes, stirring frequently.
Add the garlic, oregano, cumin and black pepper to the skillet and cook for 1 minute, stirring frequently.
Deglaze the skillet with the white wine, and cook for 1-2 minutes until most of the liquid evaporates.
Add the tomato sauce, water and the bay leaf. When the sauce comes to a simmer, lower the heat to medium-low to low, cover and cook for 15 minutes. Keep the sauce at a gentle simmer, raise or lower the heat as necessary. Stir occasionally.
Add the shredded beef, along with any broth remaining in the pot, to the tomato sauce. Stir well to combine. Cover and cook for 15 minutes, to let the flavors come together, stirring occasionally.
Remove the bay leaf and discard. Taste the ropa vieja, add salt, if needed. As a reference, we did not add additional salt to our dish.