In a saucepan, bring broth to a boil. Add pasta and cook according to package instructions.
Meanwhile, wash and core cabbage; then slice thinly.
Five minutes before the end of the pasta cooking time, add cabbage to the broth.
Rinse lemon in hot water, dry and finely zest the peel. Juice the lemon.
Separate the egg. In a bowl, whip the egg white until soft peaks form.
Stir the yolk, lemon juice and zest into the whites. Add 200 ml (approximately 3/4 cup) of hot broth; stir vigorously. Add the mixture, stirring constantly, into the broth; cook until emulsified. (Do not allow it to boil: this will cause the egg to coagulate). Season soup with salt and coarsely ground pepper. Wash dill, shake dry and sprinkle on top.