Chop the garlic and chilies with the sugar. You can use a mortar and pestle (best option), chop them finely by hand, or grind them up in a small food processor.
Transfer to a small bowl and stir in the fish sauce, lime juice, and water. Let the flavors develop for at least 30 minutes.
Notes
This can be stored in a tightly sealed container for a week in the fridge.