Place thawed oxtails in a large bowl and cover with cool water.
Add 2 Tablespoons of Apple Cider Vinegar
Let soak for 30 minutes.
Drain the oxtails. Rinse under cool running water.
Pat dry with paper towels.
Sprinkle oxtails with salt.
Sprinkle with black pepper.
Sprinkle with Worcestershire Sauce, turning to coat as needed.
Sprinkle lightly with flour, turning to coat as needed.
Place a large stock pot over Medium heat on your stove top.
Add 2 Tablespoons of cooking oil.
Place the oxtails in the pot and brown lightly on all sides, turning as needed.
Brown the ends also. This will take 5-8 minutes. Remove oxtails from pot.
Drain any excess oil, leaving about 2 Tablespoons in the pot with the browned bits.
Sprinkle 2 Tablespoons of flour in the oil.
Add a small amount of beef broth. Stir and scrape the bottom of the pot to loosen the bits.
Continue to stir and let the flour cook for one minute.
Place the oxtails back in the pot. Add enough beef broth to cover.
Bring pot to a slight boil. Cover. Reduce heat to Medium-Low.
Let the meat simmer for one hour.
After first hour, slice the onions and add to the pot. Cover again and simmer one more hour.
Remove the oxtails from the pot and set aside. They aren’t done yet.
Remove the pot of broth from the heat. Once it begins to cool slightly, spoon off the excess fat on top.
Return the oxtails to the broth. Cover and cook again until fork tender and falling off the bone.
This whole process of cooking will take about three hours.
Remove from heat when done. Serve over rice or mashed potatoes.
Enjoy!