The Thai dish of som tam, or green papaya salad, is wonderfully refreshing. In restaurants, it's served as the cook makes it. But Thailand’s street stalls and specialist som tam shops will tailor the dish to each customer's taste, with additions such as shredded carrot, dried shrimp and small salted crabs (so tiny most of the shells are edible), and they'll also ask how spicy you want it. Take the same attitude when you make it yourself and add seasonings to suit your taste.
In Thailand, som tam is usually accompanied with steamed sticky rice as a neutral backdrop to the strongly flavoured salad. It's also good with boiled rice noodles, and it can be made into a heartier meal by adding boiled salted egg or cooked prawns, or by serving it as a side dish to Thai grilled chicken with nam jim jaew dipping sauce.
Som tam should be made with a mortar and pestle. With this old-fashioned but useful implement, lightly crush (not to a pulp) some of the ingredients, such as the garlic and chillies, and gently bruise the others.
Green papaya is the fruit that's been picked before it's ripe, so it has a tart flavour and crunchy texture. Thai grocery stores sell green papaya either whole - in which case you need to peel and shred it - or pre-shredded. The latter is convenient, but use it within a few days and store it in the fridge, or it becomes mushy.
The following quantities are enough for one person; simply double the ingredients if you are serving two. Unless your mortar is very large, though, you shouldn't increase the amounts by too much.
Put the dried shrimp in a bowl, cover with warm water and soak until softened (about 30 mins). Drain the shrimp and squeeze out the excess water. Place the tamarind pulp in a bowl, add 50ml (3tbsp and 1tsp) of hot water, then stir well and leave for about 10 mins. Pour the pulp and liquid through a small sieve and press the solids to extract the flavour. Discard the solids.
Cut the long bean into 2cm (⅞in) pieces. Place the peanuts in a dry (unoiled) pan over a low flame. Shake the pan continually until the peanuts are toasted, then leave to cool.
Cut each garlic clove into three pieces. Put the pieces in a mortar and bash them with the pestle until unevenly crushed into smaller pieces (it shouldn't be crushed to a pulp, though). Add the whole bird's-eye chillies and hit them a few times with the pestle. Place the palm sugar in the mortar and use the pestle in a grinding motion to crush it to a soft paste. Add the salted crab and break it into a few pieces with the pestle. Add the peanuts, long bean and dried shrimp and hit them a few times, until just bruised.
Cut the cherry tomatoes into three or four pieces and add them to the mortar, then mix in the fish sauce, lime juice and about 10ml (2tsp) of tamarind water. Use the pestle and a long spoon held in each hand to mix and lightly bruise the ingredients. Add the shredded green papaya (and carrot, if using) and mix well. Taste the salad for seasoning; it should be well balanced, with hot-sour-salty-sweet flavours. Correct the seasonings, if necessary.
If using lettuce leaves, arrange them on a plate, then top with the som tam. Serve with steamed sticky rice or whatever accompaniments you like.