Place tenderloin in slow cooker and cover. Cook for up to 8 hours on low, or 4-5 hours on high or until temp reaches 190ºF.
In a small bowl, mix sour cream/yogurt with lime juice, zest, garlic powder and onion salt. Cover and place in the refrigerator until it’s time to serve. (This can also be served immediately but making it in advance gives the flavors time to meld together.)
When the tenderloin has reached its cook temp, remove from the slow cooker and place on a large cutting board. Using two forks, shred the meat completely. Return the pork to the slow cooker and let it sit in its juices.
Charring the corn tortillas gives them an extra boost of flavor. If you have a gas stove top, place a tortilla over each medium flame 10-30 sec per side, moving around if necessary. If your stove is electric, you can place each tortilla in a pan over medium high heat for 30 sec or until charred to your liking.
Assemble the tacos by placing a healthy serving of pork on each tortilla, followed by crumbled Cotija cheese, purple cabbage and the lime crema.