For the cooking stock: roughly chop the lemongrass. Peel the ginger and cut into small pieces. Peel the lime and cut the skin into small pieces. Place these ingredients in a poaching bag along with the pepper, thyme and the bay leaf. Fill a saucepan with 1 litre of water, add the poaching bag and simmer for 20 minutes before adding salt. Bring the stock to a temperature of 55°C.
For the beef: Heat a frying pan to hot and add a little oil. Sear the steaks for 1 minute on each side. Transfer to the cooking stock and cook for 20 minutes.
While the beef is cooking, prepare the vegetables: juice the lime. Pick and roughly chop the coriander leaves. Peel the carrots and the mushrooms and then cut into thin slices. Wash and quarter the radishes. Cut the mange-tout into slices.
Heat a wok and add a drizzle of olive oil. Cook the carrots for 3 minutes before adding the radishes, mange-tout. Cook for a further 3 minutes and then add the mushrooms, soy sauce, beansprouts, lime juice, chilli sauce. Cook for a final 3 minutes and then season with salt. Sprinkle the chopped coriander over the vegetables.
Once cooked, remove the beef from the stock and cut each steak into 3 slices. Serve the beef on a bed of vegetables. Sprinkle with a pinch of fleur de sel and some freshly ground pepper. Finish with a sprig or two of fresh coriander.
«Feel free to pan fry the steaks rather than poaching them.»