• 1 bunch choy sum, trimmed and cut into 4 cm (1½ inch) lengths
• 60 g (2¼ oz) piece of prosciutto, cut into small batons
• 1 knob of ginger, peeled and finely sliced
• 3 tablespoons sea salt
• 2 teaspoons peanut oil

Put the ginger, salt and 4 litres (16 cups) cold water in a large pot and bring to the boil. Add the choy sum to the boiling water and blanch for 3 minutes, then refresh in iced water and drain.

Heat a wok until just smoking. Add the peanut oil and, when hot, stir-fry the prosciutto for about 15 seconds, then add the drained choy sum and stir-fry for a further 30 seconds. Spoon into a bowl to serve.