To make the mousse, put all the ingredients in the bowl of a food processor and pulse to create a coarse-looking paste. Resist the urge to make it too smooth, because you still want chunks of prawn for texture. Refrigerate the mixture for at least 2 hours to firm up.
Cut the ends off the bread and slice it into
Fill a heavy-based saucepan one-third full with oil and heat to 180°C (350°F) or until a cube of bread dropped into the oil turns golden in 15 seconds. Fry each piece of toast one at a time for about 5 minutes or until the toast is golden and the prawn mousse is fully cooked. Drain on paper towels then cut each toast into
Mix the salad herbs and spring onions in a bowl, then dress with the nuoc cham.