Bring a large saucepan of lightly salted water to the boil, add the asparagus and blanch for 2–3 minutes. Drain and set aside.
Place the garlic, 1 of the chillies and the sea salt in a mortar and crush with a pestle to make a paste.
Heat a nonstick wok or frying pan over a high heat. Add the oil and heat until it starts to shimmer, then add the garlic and chilli paste and the remaining sliced chilli and stir-fry for 15 seconds until lightly golden.
Add the tofu to the pan and stir-fry until golden, then add the blanched asparagus and cashew nuts and stir-fry for about 4–5 minutes until just cooked. Stir in the soy sauce and sugar and stir-fry for a further 30 seconds before stirring in the coriander. Serve immediately with lime wedges and steamed rice.