Place beef, tomato and salt in a slow cooker. Cook for 4 hours on high or until meat is tender. Shred with two forks. Render any liquid or fat. Set aside.
Heat oil in a large frying pan over medium heat. Fill each tortilla with 3 tablespoons shredded beef. Roll and secure with a toothpick if needed. Fry each rolled taco for 3 minutes, turning frequently with tongs, or until golden and crispy. Transfer to a paper-towel-lined plate to absorb any excess oil. Repeat with remaining beef and tortillas.
Serve with lettuce, tomato, cilantro, jalapeños and cotija cheese.