Brown the beef in the pressure cooker over high heat, 5 to 7 minutes. Drain off any fat. Add the tomatoes, broth and barley and return to high heat. Close the pressure cooker and bring to up to full pressure. Reduce the heat until the cooker barley hisses, and cook for 10 minutes.
Release the pressure using the cooker's release device (read the manual), or cool the cooker by running cold water over the lid for 30 seconds. Open carefully, remove the lid and add the vegetables, herbs, salt and pepper.
Put the lid back on the pressure cooker and heat to full pressure over high heat. Reduce the heat to maintain pressure and cook another 10 minutes. Release the pressure as above. Remove the lid and cool for 5 minutes, and then serve with vinegar.
Place the pressure cooker over high heat. Oil and salt the oxtail and shank pieces then sear in batches. Add the remaining ingredients and cover with water, being careful not to fill above the cookers "maximum fill" line. Bring to a boil and skim off any foam that gathers at the surface. Cover and lock the lid. Once the pressure builds up inside the cooker, reduce the heat so that you barely hear hissing from the pot. Cook for 50 minutes.
Release the pressure using your cooker's release device (read the manual), or cool the cooker by running cold water over the lid for 30 seconds. Carefully open the lid and strain , squeezing the solids before feeding to the compost pile or the dogs. Strain through a fine sieve or several layers of cheesecloth. Season and serve or use as a base for other soup recipes.
Recipe courtesy of Alton Brown, 2011