Fish sauce is a typical sauce in Southeast Asia, especially in Thailand. It is made from salted fish, most commonly anchovies and then fermented. Spice Up! Fish Sauce gives an authentic flavor to all kinds of dishes. The secret behind the Thai curry dishes is fish sauce. It's an ingredient that gives you a little bit of everything when thrown into marinades, stir fries, and salad dressings, and it's just as useful in non-Asian cooking too. A hint of fish sauce can boost salty, savory flavor in sautéed vegetables, pastas, roast chicken or broths. Salt crystals may appear in the bottom of the bottle.