Sprinkle the short ribs with the Himalayan salt and white pepper, and coat evenly with flour. Heat the grapeseed oil in a large stockpot or Dutch oven over high. Add the short ribs and sear until browned on both sides, 2 minutes per side. Add the beef stock, carrots, celery and green pepper. Turn the heat to low, cover, and cook until the meat is falling off the bone, 2 1/2 hours.