First make the sweet and sour slaw. In a large bowl stir together the rice vinegar, sugar, salt, sesame oil, and crushed red pepper until the sugar is mostly dissolved. Wash and peel the carrot. Use a large holed cheese grater to grate the carrot into the bowl with the dressing. Add the shredded cabbage and stir until everything is coated in the dressing.
If your shredded beef is frozen, thaw and reheat it in the microwave (or stove top). Drain off the cooking liquid and then stir in the hoisin sauce until the meat is well coated in sauce.
To make the tacos, place about 1/4 cup of hoisin beef, 1/3 cup of slaw, and a few fresh sprigs of cilantro in a tortilla. Fold it up and enjoy!