1. For the noodles: In a medium saucepan heat the beef stock with the sugar over low heat, stirring, until the sugar is dissolved. Stir in the salt and the vinegar. Remove from heat, pour into a freezer proof bowl and place in the freezer.
2. While the soup is chilling, make the noodles according to the instructions on the package. Rinse well with cold water and massage to remove excess starch. Drain and set aside.
3. For the salad: Mix all of the ingredients together. To serve: Divide the noodles between two large bowls. Pour the cold broth over the noodles.
4. Top each bowl with a handful of the salad. Divide the roast beef and eggs between the bowls.
5. Grind pepper over each egg and sprinkle with sesame seeds and a bit of seaweed.
6. Serve with the rest of the salad on the side.