Combine the bird’s eye chillies, lime leaf, shrimp paste, and cherry tomatoes with brown sugar and salt in a mortar and pestle, and grind to a paste. Mix in the juice of half a lime. It should be hot, sweet, sour and salty. Add a little more salt, sugar or lime juice to balance this out. If necessary you can add a little bit of water to the mixture to make a dressing consistency.