Peel and finely dice the shallots, then remove the outer leaves from the lemongrass and finely chop the remainder.
Peel and finely grate the ginger and garlic, and finely slice the chilli. Pick the coriander leaves, then trim and shred the spring onions and set aside. Next, cut the chicken into finger-width strips.
Gently sweat the shallots in a splash of oil until soft. Throw in the lemongrass, ginger and garlic, and fry for 1 minute. Add the stock and most of the chilli.
Add the chicken and simmer for about 8 minutes or until the chicken is cooked through. Add a splash of fish sauce and squeeze in the lime juice.
Taste and add more fish sauce, lime juice or chilli as needed. At the last minute, add the coriander, beansprouts and spring onions, then divide between bowls.