Season the flank steak on both sides with salt and pepper.
Heat the olive oil in a Dutch oven over medium-high heat.
Sear the flank steak for 3–4 minutes on each side until browned, then remove it from the pot and set aside.
Add the sliced onion and bell peppers to the pot and sauté for 5–6 minutes until softened.
Stir in the minced garlic and tomato paste and cook for 1 minute to develop the flavor.
Pour in the crushed tomatoes, beef broth, vinegar, cumin, paprika, and add the bay leaf.
Return the steak to the pot, nestling it into the sauce.
Bring everything to a gentle simmer, then cover and reduce heat to low.
Simmer for 2½ to 3 hours or until the beef is fork-tender and easy to shred.
Remove the steak and shred it into strips using two forks.
Return the shredded beef to the pot and stir to coat it in the sauce.
Simmer uncovered for 10–15 more minutes to allow the sauce to thicken slightly.
Stir in the sliced olives if using, taste, and adjust seasoning if needed.
Serve hot with Black Beans and Rice