The way tender flank steak shreds into thin pieces gives this dish the name that translates literally to "old clothes." My abuela would first cook the meat in her stovetop pressure cooker, shred it and then simmer it with the tomato, onion and bell pepper sauce. In my take on this Cuban classic, I like to braise the meat right in the sauce, so all the juices marry together giving it even more depth. Some versions of ropa vieja skip the olives, capers or pimientos, but I love their salty contrast.
Pat the flank steak completely dry with a paper towel. Cut in half or thirds (across the grain) if needed to fit into your pot in a single layer. Season with 2 teaspoons salt.
Heat the olive oil in a medium Dutch oven or a large ovenproof skillet over medium-high heat. Working in batches if necessary, add the steak in a single layer and cook until a deep brown crust develops, 5 to 8 minutes on each side. Remove to a plate and set aside.
Add the onions and peppers to the same pot. Season with 1 teaspoon salt and a few cracks black pepper. Cook, stirring occasionally, until the vegetables have softened, 4 to 5 minutes. Add the garlic, cumin and oregano; stir until fragrant, about 30 seconds. Add the tomato paste and cook, stirring, until it starts to develop color, about 1 minute. Add the vino seco to deglaze and cook, scraping up any browned bits from the bottom of the pot with a wooden spoon. Add the tomato sauce, beef stock and bay leaf. Stir to incorporate. Nestle the steak in the sauce, submerging it slightly. Be sure to add any accumulated juices from the plate.
Cover and cook in the oven until the meat shreds easily with two forks, about 1 hour 30 minutes.
Transfer the pot back to the stovetop. Remove the steak to a cutting board or medium bowl and shred into long thin pieces using two forks. Meanwhile, simmer the sauce over low heat until slightly reduced, about 3 minutes. Return the steak to the pot and stir to combine. Add the lime juice and olives, capers or pimientos, if using.
Serve with white rice and black beans.
Vino seco is a golden cooking wine often used in Cuban cooking. It's available online or at markets that specialize in Cuban groceries.