1. Soak mushrooms in warm water for 30 minutes. Drain, discard woody stalks and put into saucepan with stock. Bring to the boil and simmer for 10 minutes.
2. Meanwhile, cut chicken into strips. Shred lettuce. Beat eggs with seasoning. Melt half butter in skillet, add half egg mixture and make a thin omelette. Remove from pan and reserve. Use remaining butter and egg mixture to make another omelette. Roll up both omelettes and cut into thin slices.
3. Add noodles and chicken to saucepan and simmer for 2 minutes. Remove from heat and add sherry, omelette strips and lettuce. Serve immediately.