Combine water and sugar in a bowl. Optional: heat ⅓ of the water, then mix in to make dissolving the sugar easier, then add the rest of the water.
Add lime or lemon juice in increments until you like how it tastes. A good guide is it should taste like lemonade/limeade.
Add fish sauce in small increments until you like how it tastes. It should be a little strong since it will be paired with unseasoned food.
Top with garlic and chilies then serve.
