Remove the short ribs from their packaging and place them on a plate. If there is any excess moisture on them, pat them dry using paper towels. Sprinkle both sides of each short rib with sea salt and pepper.
Heat the avocado oil in a large skillet (I recommend a 12-inch skillet for efficiency) over high heat and wait a few minutes for the oil to become sizzling hot. Place the short ribs on the hot surface in a single layer and sear for 3 minutes. Flip to the other side and sear for another 2 to 3 minutes or until a golden brown crust forms. Use tongs to transfer the seared short ribs to the bottom of your slow cooker. You may need to complete this step in two batches depending on the size of your skillet and the size of your short ribs. If you'd like, you can drain the excess fat from the skillet, but I leave it in to promote a lot of flavor.
Place the skillet back on the stove top over medium-high heat. Add the chopped onion and sauté for 3 to 4 minutes, until it begins to soften. Stir in the fresh minced garlic, fresh ginger, and Chinese 5-spice and continue cooking for another 3 to 4 minutes, stirring occasionally.
Pour the onion mixture into the slow cooker with the browned short ribs. Add the cinnamon stick and star anise.
In a large measuring cup or bowl, stir together the beef stock, hoisin sauce, soy sauce, and pure maple syrup (or brown sugar).
Pour the sauce mixture into the crock pot. It’s fine if the short ribs aren’t fully submerged in liquid.
Secure the lid on the crock pot and cook on High heat for 4 to 5 hours or Low heat for 7 to 9 hours.
Serve beef short ribs with your choice of steamed white rice or brown rice and spoon the juices from the crock pot over everything. If you’d like to make gravy, follow the steps below.
Serve with your choice of steamed rice, mashed potatoes, noodles, and vegetables. Garnish with fresh cilantro, sesame seeds, green onions, lime wedges, and sliced red chilis.