Chinese pork wonton soup

Ingredients

• 200 gram pork mince
• 1/4 cup canned water chestnuts, drained, finely chopped
• 1 teaspoon sesame oil
• 1 teaspoon soy sauce
• 1 red chilli, finely chopped
• 1 clove garlic, crushed
• 1/2 teaspoon finely grated ginger
• 20 wonton wrappers
• 2 tablespoon water
• 2 litre (8 cups) chicken stock
• 4 fresh shiitake mushrooms, thinly sliced
• 100 gram choy sum leaves, coarsely chopped