1. Defrost short ribs by soaking in water; blot dry, add soy sauce, minced ginger, garlic and Korean pear, mix well, marinate in fridge for 2 hours. Pit red dates; cut carrot, radish and mushrooms into pieces.
2. Add cinnamon in a pot, then pour short ribs with the marinade in, making sure that the liquid must cover all the short ribs, add water if there is not enough liquid. Cover pot with lid, stew about 15-20 minutes in high heat.
3. Stew short ribs until half of the liquid evaporates, add red dates, carrot, radish, chestnuts and shiitake mushrooms, pour more water into pot until the liquid comprises of 60-70% of the content inside the pot, stew a further 30 minutes with lid on.
4. Add sliced onion into pot, season with sesame oil, turn to high heat until the stew boils up, ready to serve.