Cut the onion in half and slice into 1 cm wedges (bigger slices are best). You don't have to do anything with the beef.
Put all the ingredients in a pressure cooker and turn on the heat. When the weight starts to move, reduce the heat to medium and cook for 3 minutes. Turn the heat off.
Open the lid after the pressure is released. Add grated ginger if you prefer (about 2 cm from the tube). Done!