I would only add that you can boil the bones multiple times and don't really even need the radish.
Here's my basic take:
- Put 6-8 (depending on the size) oxtail in room temp water and let it soak for an hour.
- After an hour, drain water and replace with new water. Let soak again until the water doesn't look so bloody (woof!)
- Put in water and let boil. (The water amount doesn't really matter too much)
- Boil until the broth turns white. It should go through the phases of being a clear brown and then turning white.
- Once it's white I like to put it in the fridge overnight so the fat hardens and you can scoop it out. (You can also keep the fat there if you want it a bit hardier)
- If you go the fridge route, skim fat off and boil to serve.
- For the meat, you can set them aside and let them cool. Rip all of it off and you can put salt on them separately or put a little soy sauce on them so they have some flavor on them.
- Serve broth. Add meat pieces, salt minced, minced garlic (raw and directly in the soup or you can boil a clove or two in the soup) and chopped scallions. (I like drinking it just plain with salt sometimes and with some lemon —when you wanna do the "bone broth" fad thing).
After the first boil you'll actually have another life in the meat and bones, so if you don't pick off all the meat at the first boil then you can get another round!