Peel the papaya and cut into fine strips. Soak the papayas strips in lemon water.
Peel the garlic.
Wash the beans, cut into small pieces, blanch in boiling salted water for 8 minutes then rinse in cold water. Drain well.
Wash and deseed the chillies.
Crush the chilies in the mortar with the peanuts, garlic, macadamia nuts and prawns.
Wash the tomatoes and add to the mortar together with the beans. Add the fish sauce and lime juice and lightly crush with the pestle.
Add the coconut milk.
Add a small handful of drained papaya and continue to crush.
Drain the remaining papaya. Serve on top of the salad.