1 lemon grass stalk, outer leaves discarded and finely chopped
1 banana shallot, finely chopped
1 red chilli, deseeded, finely sliced
Heat the oil in a nonstick frying pan over a medium-hot heat, add the beef fillet and sear for 4–5 minutes, turning frequently, until browned all over but still rare. Remove the fillet from the pan, pat dry with kitchen paper and wrap in clingfilm. Place in the freezer to chill for 20 minutes.
Meanwhile, mix together all the dressing ingredients in a small bowl until well combined.
In another bowl toss together the bean sprouts, spring onion, mint and coriander leaves.
Remove the beef from the freezer, discard the clingfilm and place on a chopping board. Slice the beef as thinly as possible, then arrange on 4 large plates, overlapping the slices slightly.
Scatter the bean sprout mix over the beef carpaccio, drizzle over the dressing, scatter with the peanuts and serve.