Put the beef in a bowl with the salt, lime juice and sugar and stir in the bird’s eye chillies. Mix thoroughly and leave to one side for at least 15 minutes to allow the marinade to ‘cook’ the beef.
Heat some oil in a wok or heavy-based frying pan and add the shallots. Stir-fry for a couple of minutes, then add the aubergine chunks, lemon grass, chilli paste, fish