Soak & Prep Soak oxtails in water with 2 tbsp apple cider vinegar for 30 minutes. Rinse and pat dry.
Season & Dredge Sprinkle with salt, pepper, and Worcestershire sauce. Lightly coat with flour.
Brown the Oxtails Heat oil in a large pot over medium heat. Brown oxtails on all sides (about 5–8 minutes). Remove and set aside.
Make the Gravy Base Drain excess oil, leaving about 2 tbsp in the pot. Add 2 tbsp flour and stir until golden. Slowly add beef broth, scraping up browned bits.
Simmer Low & Slow Return oxtails to the pot. Bring to a boil, then reduce heat to medium-low. Cover and simmer for 1 hour.
Add Onions & Finish Cooking Add sliced onions, cover, and simmer another hour. Remove oxtails, skim fat from gravy, then return oxtails and cook until fork-tender (about 3 hours total).
