Peel and finely chop half the onion. Set the other half aside. Peel and grate the ginger, garlic and turmeric. Finely chop the chilli, flicking out the seeds for less heat (this week's chillis pack much more of a punch than usual). Finely chop the coriander stalks, setting the leaves aside for later. Mix everything together with 1 tsp curry powder. This is your curry paste.
Finely slice the remaining onion and place in a bowl. Zest and juice the lemon into the bowl. Scrunch together with a pinch of salt and leave to marinate.
Crumble the stock cube into a jug and pour over 600ml boiling water. Stir to dissolve. Pour in the coconut milk and stir. Cut the chicken breast mini fillets into 2cm pieces.
Heat a large pan for a couple of mins. When warm, add 1 tbsp coconut or olive oil. Add the curry paste. Fry for 2 mins. Pour in the stock and coconut milk. Stir and bring to a bubble for 5 mins.
Add the chicken to the bubbling curried stock. Cook on a medium heat for 5 mins.
Drop the noodles into the pan and cook for 3 mins till just softened. Add the bean sprouts and stir. Taste and season the soup.
Ladle into bowls and spoon over the pickled onions with the lemon juice. Scatter over the chopped coriander and serve.