"Would you like to try some fish sauce?"
"I guess, how did you make it?"
"I'll tell you after you try it."
I've had this conversation a lot over the last week, since I've decanted the fish sauce that I started back in May. Most people wouldn't even consider eating seven month old fish guts, but the flavor this stuff packs belies the fact that it's made almost entirely from the waste products of processing fish.
Our local state college has a great fishery program that raises arctic char/trout hybrids. Every once in awhile, when they have a surplus of fish, they offer to sell us some to use in the cafe and sell in the store. They handle the evisceration and cleaning and provide us with ready to cook whole fish. This time I asked them to save us the viscera that they would have otherwise thrown out. I had been reading up on fish sauce and wanted to give it a go, and I knew that fish guts were the most crucial ingredient.
Many people have heard of fish sauce or cooked with fish sauce, but don't know exactly what it is or what it adds to a dish. Unlike the name suggests, fish sauce doesn't add the flavor of fish to foods that it's used it. Used properly, it actually doesn't add much flavor at all. What fish sauce really brings to the table is umami richness, umami being the "fifth taste" that confers savory, meaty, rich flavor. It's much more ethereal than the four stalwart tastes, sour, bitter, salty, and sweet. Umami wasn't classified as a taste until 1908, but once you learn that it's present in foods like soy sauce, miso, shiitake mushrooms, tomatoes, and hard cheeses, it's easy to pick it out. It's the flavor that makes you close your eyes and sigh on the exhale after taking a bite, and fish sauce is full of it.
The mechanism behind this sensation relies on the way our bodies respond to L-glutamate, an amino acid. Amino acids are the building blocks of proteins, but in order to experience the umami flavor from them you have to deconstruct the proteins into their constituent amino acids. This is often done via bacteria, yeasts, or molds in fermentation. While there is some fermentation present in fish sauce it's not the primary driver of the reaction. The process is enzymatic, driven by digestive enzymes. Enter the fish guts.
The viscera (or guts) are full of digestive enzymes that can break down any proteins in the fish parts and turn them into amino acids. In combining the guts with some fish scraps, water to cover, and enough salt to deter spoilage bacteria, you can harness that power to turn waste into liquid gold. And that's exactly what I planned to do.
Upon returning home with my fish guts they didn't look like much. A couple of plastic bags of wobbly bits peppered with gills. I filleted a couple of the whole fish to cook with and added their heads and bones to a big food grade bucket, along with the fish guts, a head of garlic, a palmful of peppercorns, a few bay leaves, and enough water to cover it all. I then added just enough water to cover it all and tallied up the weight. To that I added 12% of the weight in salt, and stirred well. I hammered on a lid with a brand new gasket, labeled it "FISH SAUCE: DO NOT OPEN INSIDE", and put it at the bottom of a stack of other buckets, just for good measure. Then I forgot about it for a while.
After a month I took the bucket outside, far from the building, and took a peek inside. I was pleasantly surprised to note that the smell was remarkably mild, just a little like canned tuna. The flavor wasn't bad either. Definitely fish, but not rotten. I put it back and continued to check up on it every couple weeks. Finally it reached a point where the flavor seemed to be unchanging. At that point I transferred it to a big glass jar so that I could monitor it visually to see where the sediment fell and where clear fish sauce gathered. The Romans, when making garum, called the clear garum "liquamen" while referring to the cloudy paste left behind as "allec". I wanted pure liquamen for my fish sauce. It took a long time to settle, but the liquamen finally made a clear layer in the middle, with the allec floating on top and some stubborn bones and sediment on the bottom. The fish heads almost entirely dissolved, and there wasn't anything recognizable as fish left in it.
At that point I siphoned off a quart or so to sample. Wow. Very clean tasting, rich, salty, and immensely satisfying. Hardly any fish flavor or odor. I was just thrilled with it. To gauge my success I tasted it side by side with Red Boat (commonly regarded as the best commercial fish sauce) and another brand of store bought fish sauce. While it didn't quite hold up to the Red Boat, it was immensely better than the average store bought fish sauce. Despite this, the fact that I made it myself, utilized a waste steam, and was able to support local agriculture while doing it makes it much more valuable to me than any bottle of Red Boat has ever been.
One of my favorite uses of fish sauce is in nuoc cham, a Vietnamese dipping sauce. WIth only four simple ingredients it's salt, sour, and sweet, the perfect way to add a burst of pungent flavor to fresh spring rolls, rice, salads, and fish. My version packs quite a punch, which I like with the mildness of the foods usually served with nuoc cham, but you can easily temper it by adding another tablespoon of water. This is a recipe that really requires you to taste and adjust to get it just right, seeing as different brands of fish sauce and the flavor of limes vary so greatly. You'll get a good idea of some basic proportions though.
Makes a little over 1/4 cup
2 Tbsp fish sauce
2 Tbsp fresh lime juice
2 tsp honey
1 Tbsp water
Optional: garlic, fresh Thai chili or chili paste
Combine ingredients and mix well to dissolve honey. Taste, adding more of any one ingredient as necessary. The fish sauce should provide enough salinity for the sauce to be just on the cusp of too salty. Because it is a thin consistency it doesn't cling to food, and as such will need to be stronger than thickened sauces. Serve with spring rolls, lettuce wraps, fish or shrimp, or salads. I enjoy using it to dress a cucumber and shrimp salad with shallots