Stir the sugar into the warm water until fully dissolved. Warm water matters — sugar will not dissolve well in cold water.
Add the fish sauce and lime juice.
Stir in the minced garlic and sliced chile. Some cooks like the garlic to float on top; either way is fine.
Taste and adjust: more sugar if it is too sharp, more lime if it is flat, more fish sauce if it needs depth, more water if it is too salty. Tasting as you go is the step that makes the recipe yours.
Rest 10 minutes so the garlic and chile infuse. Serve at room temperature.