Chinese wonton soup

Ingredients

• 1 kilogram chicken bones
• 1 small_piece brown onion (80g), quartered
• 1 medium_piece carrot (120g), quartered
• 3 litres (12 cups) water
• 4 centimetre piece fresh ginger (20g), grated
• 2 fresh small red thai chillies, halved lengthways
• 150 grams pork mince
• 1 clove garlic, crushed
• 1 green onion, chopped finely
• 2 tablespoons finely chopped water chestnuts
• 2 tablespoons finely chopped fresh coriander
• 1 teaspoon sesame oil
• 2 tablespoons chinese cooking wine
• 1/4 cup (60ml) soy sauce
• 2 teaspoons caster sugar
• 12 wonton wrappers
• 1 cup firmly packed watercress sprigs
• 4 fresh shiitake mushrooms, sliced thinly