1. Soak and process shark's fin.
2. Shred chicken; then dredge lightly in cornstarch. Mince smoked ham and scallion stalks.
3. Bring stock to a boil. Add shark's fin and simmer, covered, 20 minutes. Add chicken; simmer, covered, 10 minutes more.
4. Season with salt. Garnish with ham and scallion and serve.