Chicken and Coconut Soup

900ml (1 1/2 pints) homemade chicken stock

1 x 400g (14oz) can coconut milk

8 thin slices of fresh ginger or galangal

2 lemongrass stalks

1 tablespoon red curry paste (we use Mae Ploy)

1 - 2 tablespoons sugar

1/2 onion (50g/2oz), thinly sliced

225g (8oz) crimini or brown mushrooms, thinly sliced and slivered if larger

5 tablespoons fish sauce

225g (8oz) chicken breast, very thinly sliced

1/4 - 1/2 teaspoon salt

2 limes, juiced (at least 50ml/2fl oz or more to taste)

1 tablespoon grated lime zest

20g (3/4oz) fresh basil leaves (use Thai basil if available)

110 - 225g (4 - 8oz) cooked white rice (optional)

To serve:

fresh basil leaves