While oxtail meat is naturally flavorful, improper cooking can leave it tough and difficult to chew. Because of this, cooking oxtails in your oven requires a combination of moisture and time in a cooking method called braising. Moisture can come in the form of a marinade that assists in tenderizing oxtails prior to oven cooking or it can be liquid you add to a roasting pan. Time ranges from about 1 1/2 hours for oxtails you marinate to three or more hours for oxtails you add directly to a roasting pan.
Remove excess fat with a sharp kitchen knife and then brown oxtails on all sides to release flavor molecules on the surface of the meat. You can brown oxtails in 1 to 2 teaspoons of olive oil in a skillet on your stove for five to seven minutes, or in a roasting p[an in a hot, 450 degree Fahrenheit oven, for 30 to 40 minutes before reducing the oven temperature and adding cooking liquid.
Add enough cooking liquid to partially submerge the oxtails. As an estimate, you need about 1 to 1 1/2 cups of liquid for each pound of oxtails. The liquid you use can be water, low sodium chicken or beef broth, cooking wine, balsamic vinegar or any combination that suits your taste preference.
Cover the roasting pan. Although you can cover a roasting pan with a sheet of aluminum foil, a roasting pan with a tightly fitting cover will do a better job of retaining heat and moisture within the pan.
Preheat your oven to 325 degrees Fahrenheit if you do not first marinate the meat and 350 degrees Fahrenheit if you do. The reason the difference relates to a longer cooking time for oxtails you do not first marinate.
Braise the oxtails for 1 1/2 hours if you first marinate the meat and about two hours if you do not. Test the meat to estimate remaining cooking time with an instant read meat thermometer. The temperature of the meat should be at least 150 degrees Fahrenheit before removing the roasting pan from your oven.