Heat up the beef broth on the stove and mix in the soy sauce, fish sauce, tomato paste, and butter.
Place in the slow cooker with the oxtails.
Season with spices.
Cook on low for 6-7 hours.
Remove the oxtail from the slow cooker and set aside on paper towels to drain (if you are going to serve them dry).
Add 1/2 tsp.
Guar Gum to the remaining juices.
Use an immersion blender to blend and thicken.
Serve with Cauliflower Mashed Potatoes or your favorite fatty side dish with gravy on top.