Prep the tacos ahead by making the tuna mixture and the cabbage slaw and storing them separately in the refrigerator for up to 3 days. If you're really sort on time, buy pre-shredded coleslaw mix, which usually contains grated carrots.
In a bowl, mix the tuna, lime juice, onion, cilantro, oil, salt, and black pepper.
In a separate bowl, combine the cabbage, carrots, and jalapeno peppers with their juice.
Warm the tortillas according to packaging directions. Top with the tuna mixture, red cabbage slaw and more chopped cilantro.