In a bowl, soak the beef in cold water for about 20 minutes to draw out the blood, then drain. In a medium pot, add enough water to cover the beef. Over high heat, bring to a boil. Skim off any scum that forms. Lower the heat to medium low and simmer covered for about 1 ½- 2 hours, or until tender. Add more water as needed. Remove beef from water and let it cool. Set aside in the refrigerator and save reserved broth in a separate container. Remove any fat that forms. This is easier to do when the broth is chilled.
In a blender, purée the ingredients for the sauce until smooth. Set aside the mixture, cover, and refrigerate until ready to use. If you can’t prepare this sauce the day before, place in the refrigerator for about an hour or two before serving to give the ingredients a chance to meld.
In a medium bowl, whisk together the pickling ingredients for the radish (salt, sugar, and vinegar). Add the slices of radish, toss to coat, and set aside for 20 minutes to wilt. Make sure to toss the radish in the liquid occasionally. Rinse with water, and squeeze gently to remove excess moisture. Set aside.
Cook the noodles only when you’re ready to serve. In a large pot, bring water to a boil. Cook the noodles for about 2-3 minutes, until soft, but slightly chewy and elastic. Drain and rinse with cold water well. Hold the noodles in your hands and rub them under the running water, as if you’re doing the laundry by hand. Divide the noodles into 4 piles. It’s okay for the noodles not to be well drained. This will help to thin out the sauce slightly, making it easier to mix with the sauce in the bowl.
Cut the beef along the grain in very thin slices. Cut hard boiled egg in half lengthwise. Place a mound of noodles in the center of the bowl. Place a pile of pickled radish on one side of the noodles. Next to the radish, fan the sliced beef, and next to the beef, add the julienned pear and cucumber. Leave a space to spoon some of the bibim sauce on top of the noodles. Drizzle with some sesame oil (especially over the beef), and sprinkle with sesame seeds. Add half of a hardboiled egg in the center. Serve immediately.