Cover your short ribs in kosher salt and brine in the fridge for a minimum of 1 hr and up to 12. Pull out of the fridge 30 min before searing.
Preheat a braising pan for 5 min on med heat. Sear the short rib until deeply golden on all sides. Set aside.
Add in onion, green onion, garlic and ginger. Sautee until golden, about 7-8 min on medium heat. Add in miso, gochujang, black peppercorns, maple, mirin and rice vinegar. Mix and cook for 2 min.
Add in the meat and top with the beef broth.
Bring to a simmer, cover and bake at 375F for 30 min, lower to 325F and braise another 2 hrs or until very tender.
Remove beef from the pan.
Strain the leftover liquid squeezing as much as you can out of the veg.
Add to a sauce pan and simmer. Make a slurry with the corn starch and some of the hot broth. Add a bit at a time until desired thickness.
Add the leeks to a pan, coat in olive oil and fry until lightly golden.
Add the beef to the thickened sauce to warm up.
Serve over potato puree with the leeks, more sauce and chives.
