1 tablespoon vegetable oil
2 pounds beef flank steak
1 cup beef broth
1 (8 ounce) can tomato sauce
1 small onion, sliced
1 red bell pepper, seeded and sliced into strips
1 green bell pepper, seeded and sliced into strips
2 cloves garlic, chopped
1 (6 ounce) can tomato paste
1 teaspoon ground cumin
1 teaspoon chopped fresh cilantro
1 tablespoon olive oil
1 tablespoon white vinegar
Heat vegetable oil in a large skillet over medium-high heat.
Brown the flank steak on each side, about 4 minutes per side.
Transfer beef to a slow cooker.
Pour in the beef broth and tomato sauce, then add the onion, bell pepper, garlic, tomato paste, cumin, cilantro, olive oil and vinegar.
Stir until well blended.
Cover, and cook on High for 4 hours or on Low for up to 10 hours.