Heat oven to 325ºF (170ºC). Season the short ribs all over with salt and pepper then dust with flour. Heat a 7-quart Dutch oven over medium-high heat, add the oil and heat through.
Working in batches if needed, as to not overcrowd the pan, sear the ribs on all sides, about 5 minutes total. Remove to a plate and repeat with the remaining ribs.
Return the pot to medium heat and add the shallots and ginger, sautéing until the shallots are tender, about 5 minutes. Stir in the miso paste followed by the soy sauce, brown sugar and beef stock.
Return the short ribs to the pot with the garlic and bring to a boil over medium heat. Cover the Dutch oven and move it to the oven and cook, turning the ribs half way through cooking, until the meat is fork tender, about 3 to 3½ hours.
Serve the short ribs over crispy rice with greens. Ladle the additional sauce over the top of the short ribs, then garnish with sesame seeds and green onions then serve.