NO
WE DO NOT "BOIL" MEATS
WE DO NOT BROIL OXTAILS!
Basic any kinda soup, adapted for oxtails:
Get a pot of water and boil it.
Put the oxtails in.
Put in some chopped celery, coarsely chopped carrots, a whole peeled onion, and if you feel like having potatoes in there, some potato chunks or baby potatoes.
Bring it back to a boil.
While it's coming back to a boil, throw in a good bit of salt, some whole peppercorns, and 2-4 dried bay leaves.
Optional, any or all of: 1/4 - 1/2 teaspoon cayenne; sprig fresh rosemary, thyme, sage tied together-- this is called "bouquet garni" by the Damn French and it adds a lot and is usually sold in a decent supermarket produce section in a little plastic herb package.
As soon as it boils, reduce it all the way back down to a simmer, where bubbles just break the surface. You do not want to sit there boiling the living crap out of it.
Simmer LOW for an hour or two, depending on your patience, preferably 2. While it simmers, now and then, skim off any foam or grease that comes to the top. Taste to make sure you have the right amount of salt and cayenne.
If you didn't want potatoes but you want some starch in there, you can throw in some pasta (not much or it will cease to be soup) near the end, bring it back to a boil, then reduce again to simmer til the pasta is done.
Or you can serve it over rice, or by itself, or whatever.
Mushrooms? Fresh or canned, you can throw those in at the end.
Serve and finish with none or any or all of: red wine vinegar, dill weed, cilantro, chives, chopped scallion, or whatever.
That's basic soup.
Oxtails must not be broiled or otherwise cooked with dry-heat methods.