Rachel’s crab and prawn coconut soup

2 tbsp sunflower oil

2 small garlic cloves, peeled and sliced

½ tsp ginger, grated 

1 tsp lemongrass, finely chopped

200g crab meat

500ml fish or light chicken stock

1 tin of coconut milk

1 tbsp fish sauce (nam pla)

50g raw prawns, peeled

2 spring onions, trimmed and finely sliced

juice of ½ lemon

¼ red chilli, deseeded and finely chopped

1 tbsp fresh coriander, leaves and stalks

salt

pepper