Toast the peanuts in a large dry frying pan over a medium-high heat, transfer to a bowl and set aside. Peel and finely slice 2 cloves of garlic, roughly chop most of the prawns and the tomatoes.
Return the frying pan to a medium-high heat with 1 tablespoon of oil and the garlic. Fry for 1 minute, stir in the whole prawns and fry until turning pink, then add the chopped prawns. Cook for another minute, stir in the tomatoes, then cook for 2 to 3 minutes, or until softened. Remove from the heat and leave to cool.
Deseed the chillies and peel the remaining clove of garlic, then roughly chop. Place into a pestle and mortar and pound to a rough paste. Add half the toasted peanuts and bash well. Squeeze in the juice from 2 limes, add the fish sauce and 2 tablespoons of honey, then mix well. Taste and add more lime juice or honey, if needed, then place into a large bowl.
Halve the cucumber lengthways, scoop out the watery seeds, then very finely slice with a mandolin (use the guard!). Peel and very finely shred the green papaya (or the cabbage, if using), then add to the dressing.
Trim and finely slice the spring onions, pick and roughly chop the basil leaves, then add to the bowl with the whole coriander leaves. Add the cooled prawn mixture and toss well. Roughly chop and scatter over the remaining peanuts and serve with lime wedges for squeezing over.