2. Simmer on low for 45 minutes.
3. Pass the soup through a strainer (straining out the star anise and cinnamon) onto the peeled and diced rhubarb reserved in a bowl.
4. Let cool. Cover and refrigerate overnight.
For the bisquit:
5. Beat the egg whites and sugar with an electric mixer until stiff peaks form.
6. Fold in the egg yolks, followed by the flour.
7. Place in buttered and floured 9-inch cake pan.
8. Bake at 350° F for 15-20 minutes until a toothpick comes out dry.
9. Let cool and invert cake onto a cutting board (it should be light and fluffy).
10. Cut out 4 circles large enough to hold a scoop of sorbet. (You will have at least half of the cake left over, so save and enjoy later.)
For the presentation:
11. Pour rhubarb syrup into shallow soup bowl.
12. Place bisquit in center.
13. Place scoop of sorbet or ice cream on top.
14. Garnish with diced mango.