Comment by kriro

I cook a lot of Vietnamese food. Goto recipe for fish sauce to use with bánh xèo and the like is roughly 4:1 water to fish sauce (3:1 is also fine) mix with 1-1.5 tablespoons of sugar until the sugar is dissolved.

Chop 2-3 pieces of garlic and roughly the same amount of chilli into very fine pieces (same cutting board so they mix already while chopping) and add it. Then squeeze about a slice of lime. taste and up/down sugar/acidity/fishiness to taste.

Edit: Typically I use 3 tablespoons of nước mắm with 12 of water for the 4:1 (forgot that in the initial post, otherwise the sugar amounts and so forth make little sense).