Blitz together the sunflower oil, chilli, garlic, ginger, shallots, turmeric and coriander stalks in a food processor until you have a paste. Scrape into a large saucepan set over a moderate heat and stir-fry for 1-2 minutes until fragrant. Add the coconut milk, chicken stock and lime juice and stir well to combine. Bring to the boil, then reduce to a gentle simmer. Add the chicken to the saucepan along with the fish sauce, sugar and soy sauce and simmer for 5-6 minutes until cooked through with no pink showing. Blanch the beansprouts for at least 15 seconds in boiling water and allow to cool. Then add them to the broth. Drain the noodles and toss in the sesame oil. Divide the noodles evenly between 4 metal soup bowls. Spoon the broth on top and garnish with coriander leaves before serving. Freezing and defrosting guidelines Make the soup, then leave to cool at room temperature. Freeze (without garnishes or toppings) in a rigid container, leaving a bit of space for expansion, for up to 1-3 months. Reheat either from frozen or defrost in the fridge overnight. Once piping hot, add toppings or garnishes and serve.