01 -
Heat the vegetable oil in a large skillet over medium-high heat. Once hot, add the flank steak and sear until nicely browned, about 4 minutes per side. This step creates a flavorful crust on the meat.
02 -
Transfer the seared flank steak to a slow cooker. Pour in the beef broth and tomato sauce, then stir in the tomato paste until well combined.
03 -
Add the sliced bell pepper, sliced onion, minced garlic, ground cumin, chopped cilantro, olive oil, and vinegar to the slow cooker. Stir gently until all ingredients are well distributed around the meat.
04 -
Cover the slow cooker and set it to cook on Low for 8-10 hours, or on High for 4 hours. The meat is ready when it's tender enough to easily shred with a fork.
05 -
Once the beef is tender, use two forks to shred the meat directly in the slow cooker. Mix the shredded beef thoroughly with the sauce and vegetables before serving.