A very hot dip served with sticky rice or grilled vegetables. Charring the ingredients on a barbecue improves the flavour no end, but a grill pan does an acceptable job.
Heat a dry grill pan over a high heat and add the garlic, chillies and shallots. Fry for 4–5 minutes, stirring, until fragrant, then leave to cool before cutting them into small chunks.
Transfer to a mortar with the tomatoes. Using a pestle, grind to a paste.
Add the oil, nam pla, lime juice, coriander and sugar and mix well.