To make yeast dough, stir sugar into water; sprinkle with yeast.
Let stand 5 minutes or until frothy.
Stir gently.
Put flour and salt into a bowl.
Add yeast mixture liquid and starter dough to make a dough.
On a floured surface, knead until smooth.
Cover and let rise overnight at room temperature.
To make filling, melt butter in a skillet; season chicken and cook gently in butter.
Cool.
Mix green onions, mushrooms, sausage, herbs, 1 egg yolk, half-and-half, coriander and allspice in a bowl.
Preheat oven to 400°F (205°C).
Mold sausage mixture around each chicken portion.
Flour a baking sheet.
Knead dough.
Roll out 1/4 inch (5 mm) thick.
Cut into 4 rounds; place a chicken portion on each.
Fold dough over chicken; press edges together.
Place on baking sheet.
Brush with egg yolk; sprinkle with caraway seeds.
Bake 30 minutes or until golden.