Heat oil in large heavy-bottomed pot over medium-high heat. Season meat with adobo. Add steak to pot and cook in batches, flipping once, until well browned, about 10 minutes. Transfer meat to a plate. Lower heat to medium. Stir in onions and peppers. Cook, stirring occasionally, until vegetables are soft, about 10 minutes. Add Sofrito and garlic to pot; cook until fragrant, about 1 minute.
Stir in 3 of cups water, tomato sauce, Sazón, beef bouillon and pepper. Bring mixture to a boil. Return beef to pot. Lower heat to medium low and simmer, covered, stirring occasionally, about 45 minutes. Stir in olives and capers. Cover pot; simmer until meat shreds easily with fork, 1 – 1½ hours, adding more water in ¼ cup measurements, if pot becomes dry.
Transfer meat to work surface; shred meat with two forks. Bring remaining sauce to a boil. Mix meat and cilantro into sauce. Serve with white rice.
The key to a successful Ropa Vieja is flank steak. The reason: this type of meat is the perfect candidate for a low, slow cooking process; as the meat slowly cooks in the simmering liquid, the fat and connective tissue melt, and baste the meat from the inside out. The results: fork-tender meat that shreds effortlessly. If flank isn’t available at your market, skirt steak and chuck work great, too.