Ginger chicken and bok choy noodle soup

Ingredients

• ramen or rice noodles for 4 people
• 1 tablespoon sesame oil
• 1 or 2 small boneless chicken breasts, finely chopped or minced
• 1 1/2 tablespoon grated ginger
• 1/2 cup sliced mushrooms
• 1/4 teaspoon dried chilli flakes
• 3 cups Shanghai bok choi, thinly sliced, green and white parts
• 6 cups chicken stock (preferably liquid stock)
• 1 1/2 tablespoon soy sauce
• sliced spring onion and toasted sesame seeds to garnish (optional)