In a mixing bowl, combine the coconut aminos, beef broth, keto-friendly sweeteners, minced garlic, grated ginger, sesame oil, and crushed red pepper flakes if using. Whisk together until smooth.
Place the beef short ribs in a large resealable bag or a bowl. Pour the marinade over the ribs, making sure they are well coated. Seal the bag or cover the bowl and refrigerate for at least 2 hours, or overnight for optimal flavor.
Remove the short ribs from the marinade (reserve the marinade for later). Heat a large pot or Dutch oven over medium-high heat. Add the short ribs in batches, browning them on all sides for about 2-3 minutes per side. Transfer the browned ribs to a plate.
In the same pot, pour in the reserved marinade and bring it to a simmer. Add the xanthan gum (or cornstarch mixture if not keto) and whisk until the sauce thickens slightly.
Return the short ribs to the pot, ensuring they are covered with the sauce. Cover the pot and reduce the heat to low. Let them simmer for about 2-3 hours, or until the ribs are tender and the meat is falling off the bone.
Once done, transfer the ribs to a serving platter. Drizzle with additional sauce if desired and garnish with sliced green onions and sesame seeds.
