What part did you buy? It’s so difficult to do. My father loves to eat beef tendon. He buys beef tendon every time he stews beef. After stewing it in a pressure cooker for forty minutes, it will usually become very soft. You can eat it after the pressure cooker runs out of steam. It is delicious hot or cold. After turning off the heat, it's best to simmer and don't rush to open the pot. If the beef is old. Before you make it, it’s best to grind the ginger into puree and marinate it for a few hours. In fact, ginger is the best meat tenderizer, comparable to meat tenderizer but completely harmless. If you don’t like to eat beef with a lot of soup, wait until the pressure cooker is done and then return it to the wok over high heat to collect the juice (actually, you can just run out of steam in the pressure cooker, open the lid and collect the juice over high heat)