In a blender combine the onion, garlic, maple syrup, apple cider vinegar, beef broth, ancho chile powder, cumin, salt, pepper and beef bone broth collagen. Blend until smooth and set aside.
Heat a large cast iron or non-stick skillet over medium-high heat.
Pat the short ribs dry and sprinkle with salt and pepper.
Brown the short ribs in batches, searing every side. This will take approximately 5-7 minutes per batch.
Place the browned short ribs into the slow cooker and cover them with the ancho chile sauce.
Cover and cook for 6-8 hours or until the meat is very tender.
Remove the ribs from the slow cooker, discard the bones and shred the meat.
Skim the fat from the sauce and discard.
Return the shredded meat to the sauce and mix together. Season with salt and pepper as needed.
Serve the meat in corn tortillas topped with sliced radishes and cilantro.
If you make this the day before serving, refrigerate the meat and sauce in separate containers. Remove and discard the hardened, separated fat from the top of the sauce before combining the meat and sauce and reheating.
To keep this recipe Paleo, serve the tacos in grain-free tortillas, lettuce wraps or on cauliflower rice.