Place the peanuts in a small frying pan over medium-low heat. Stir and cook the peanuts until they're golden and aromatic. Transfer the peanuts into a small bowl and set them aside for later.
Slice the tip and end of the papaya, then use a vegetable peeler to remove its skin. Cut the papaya in half and use a spoon to scoop out the seeds. Use a shredder (I got mine at an Asian shop) or mandoline to shred the papaya into thin long strips. Remove as much flesh as possible until it reaches the seed. Place the shredded papaya into a bowl and set aside for later.
For the sauce - In a small bowl, mix the fish sauce and lime juice. Peel the prawns, devein them and slice them lengthwise (horizontally) in half. Set the sauce and prawns aside for later.
For the chilli shrimp paste - Place the dried shrimps into a food processor and blitz until the prawns resemble fine breadcrumbs, then transfer the dried shrimps to a mortar bowl. In the same processor bowl (no need to clean first), place the garlic and chillies and pulse until finely minced, then add it to the mortar bowl along with the shrimps. Pound the ingredients together with the pestle until it forms a paste. Spoon the paste into a large bowl. There's no need to clean the mortar before pounding the palm sugar.
Place the palm sugar into the mortar bowl. Break the palm sugar with the pestle into large pieces. The sugar is quite sticky, so add a few tablespoons of sauce and continue to pound and grind (adding the sauce will help the sugar dissolve). Continue adding tablespoons of sauce in between grinding until it's finished. There should be no lumps of palm sugar remaining.
For the dressing - Pour the palm sugar mixture into the large bowl with the chilli shrimp paste and give it a good mix.
Place the beans into the mortar and pound it a few times and crush the beans slightly, then remove to a small bowl, and do the same with the roasted peanuts.
Add the papaya, prawns, tomatoes, snake beans, and peanuts into the large bowl with the dressing and give it a good mix. Optional - Display some prawns on the top of the salad and garnish with Thai basil leaves, chilli and peanuts.