Compelling, pungent, and stinky are some of the terms used to describe this sauce used in southern China and Southeast Asia. Though made in a similar manner as fish sauce, shrimp sauce (mắm ruốc/mắm tôm) is thick like toothpaste and purplish in color. For Western palates, it’s probably the hardest Asian fermented seafood product to accept. (But what about a ripe, room temperature camembert or Roquefort? They’re quite heady too.) Shrimp sauce isn’t eaten right out of the jar. A bit of it is blended into foods or dipping sauces, where it imparts an aroma and savoriness that deepens the overall qualities of a dish. Think of it as a stealth ingredient for injecting umami into foods. Central and northern Viet cooks have a penchant for the sauce, and add it for the signature flavors of classics such as bun bo Hue (spicy Hue beef noodle soup) and bun rieu cua (crab and tomato soup). I've used mam tom shrimp sauce for making a Southeast Asian spicy umami ketchup.
Sold in jars at Chinese and Southeast Asian markets, shrimp sauce may be smooth or coarse. I prefer the smooth version labeled “fine shrimp sauce.” Koon Chun and Lee Kum Kee produce great shrimp sauce. There is shrimp sauce coming from Vietnam but the consistency of those products can waver. Buy a small jar as a little goes a long way!
Refrigerate shrimp sauce to keep its smell at bay. When measuring shrimp sauce for recipes, use a small plastic spatula to push it out of the measuring spoon so that you won’t have to touch it. Malay and Indonesian blanchan (aka belacan and trassi) are similar in pungency if not a little more intense.
Have you experience with shrimp paste? Feel free to note positive and negative feelings!