Soak the papaya for about 15 minutes in ice water to help make the papaya crunchier. Drain well and place on a towel-lined plate to absorb excess water.
In the mortar, pound garlic and chilies into a rough paste.
Add the palm sugar and mash with the pestle until it turns into a wet paste.
Add the long beans and pound just until they're broken.
Add the dried shrimp and peanuts and pound to break the peanuts up slightly.
Add the fish sauce, tamarind paste, and lime juice, adding the squeezed lime skin into the mortar as well. Stir with a large spoon to mix and dissolve the sugar.
Add the shredded papaya and tomatoes, and mix using the pound-and-flip method until well mixed.
Plate and sprinkle with extra peanuts, if desired.
