Pop the pork tenderloin in your slow cooker and add all of the other ingredients to the pot. You don't need to make sure everything is evenly distributed right now - after it's been cooking for half of your cooking time, give everything a stir and make sure everything is evenly distributed.
Cook at 1.5 - 2 hours on high heat, or 3.5 - 4 hours on low heat.
When the cooking time is up, shred the pork into large chunks with two forks. The meat will be very tender and the process won't take long at all. Serve with some of the wilted onions and garlic cloves, over a big helping of mashed potatoes or polenta to soak up all that juice!