1. In a food processor, add the tomatoes, onion, salt and pepper and blend until the mixture looks coarsely chopped.
2. Using a sharp knife cut the steak into 2-inch cubes. Pat dry the steak and season it with salt and pepper on both sides.
3. In a large skillet over medium-high, heat the the vegetable oil. Add the meat and cook for about 2-3 minutes per side or until it has seared (browned) on all sides .
4. Once done, pour in the taco sauce and stir well.
5. Add in the tomato and onion mixture and stir for 2 minutes.
6. Add in the salsa, jalapeno peppers, garlic, cilantro and mix until well combined. Reduce the heat to medium low. 7. Add a generous amount of salt and pepper. Simmer for 3 1/2 to 4 hours or until the meat breaks apart with a fork.
8. Fill the tacos with this steak sauce and serve hot garnished with chopped lettuce and shredded carrot.
If sauce looks thick, fill salsa jar half way with water and add to steak sauce.