In the bottom of a pressure cooker, heat the olive oil then add the onion, short ribs and flanken and brown on all sides. Should take around 10 minutes.
Add the water, close the pressure cooker and cook for 20 minutes. When the pressure comes down, refrigerate the meat for 2-3 hours or freeze for 1 hour. The fat will congeal on the top of the meat and you can skim it off before continuing the process.
Add the tomato juice and bring to a boil.
Add the sugar, lemon juice and cabbage. Then add the baking soda, stir quickly and let it foam up.
Place the cover on the pressure cooker and cook for 25 minutes.
Once the pressure comes down, take off the cover and continue boiling the soup for 1 hour or more. Just keep cooking the soup until the meat is falling off the bone.
Note: if you don’t have a pressure cooker, you can make this soup in a regular pot. Just boil the soup for 3-4 hours.