A good tropical soup does more than warm a bowl. It wakes up the kitchen with lime, coconut, chiles, herbs, seafood, leafy greens, and slow-simmered broths that taste tied to place.

A few drops of fish sauce can make a thin soup taste like it simmered all afternoon. It adds salt, yes, but also savoriness, depth, and a gentle roundness that plain salt cannot bring on its own.