Ketchup may be the king of all condiments. It's a ubiquitous presence on tables in just about every home in North America, and its sweet, tangy flavor is as familiar and reassuring as a hug. Ketchup seems quintessentially American, yet it's evolved dramatically from Asian roots into the product we know and love today. So what makes ketchup, well...ketchup?

The way to make a really authentic ketchup is simple but surprising. First, take some dead fish. Lay them in a clay pot. Cover with salt. Then leave it out in the sun for several days to ferment and liquefy. Ta-da! You now have ketchup.

If you think that sounds a lot like fish sauce, you may be on to something. The word "ketchup" comes from a dialectical Chinese word "ke-tsiap," which loosely translates as "fish brine." It's the same recipe and possibly the same culinary root as modern Thai fish sauce, nam pla. So how did something so salty and fishy turn into something tangy and tomatoey?

History tells us that it was most likely 17th century British explorers and traders who first brought ketchup west, having learned the word from the Malay people in what is now Indonesia. They used the word "kecap" to describe a range of sauces, including soy sauces. The first known printed English-language recipe to bear the name "ketchup" comes from Eliza Smith's The Compleat Housewife in 1727. Her key ingredient? Anchovies. At the time, many people regarded tomatoes with suspicion, believing plants in the nightshade family to be poisonous.

Later recipes favored mushrooms, walnuts, or oysters—all excellent sources of umami—and some recipes bore a striking resemblance to the original fish sauce technique. Mushroom ketchup, for example, was made by layering mushrooms with salt in a clay pot and leaving them to ferment and break down. Spice and strong wine or stale beer might be added to aid preservation and encourage fermentation.

The first true tomato ketchup recipe came in 1812 from a Philadelphia horticulturist named James Mease, who advised layering tomato slices with salt, leaving for a day, and then mashing and simmering the pulp. He added mace, allspice, cloves, shallots, and brandy. A British cookbook published a few years later contained a recipe for tomato sauce with anchovies, and another for tomato sauce with vinegar. But it wasn't until 1876 that one man popularized the tomato-and-vinegar concoction we think of as ketchup today, and his name was Henry John Heinz.

Heinz was a bottled horseradish salesman who diversified into pickles and sauerkrauts and struck gold with bottled tomato ketchup. Heinz was not the first to sell prepared tomato ketchup, but he was a gifted marketer who advertised extensively, built up his business internationally, and even lobbied Congress to pass a pure food act that both benefited consumers and forced some of his rivals out of business. Heinz was also the smart fellow who thought to sell his products in clear glass bottles to assure customers that they were unadulterated. Heinz Tomato Ketchup was a huge success. It not only established the Heinz company, but also the primacy of the tomato among ketchups. Today Heinz owns 60% of the ketchup market in the US and sells 650 million bottles annually around the world.

Modern prepared ketchup follows a fairly simple manufacturing process. Tomatoes are pulped and cooked into a concentrate, seasoned, strained, bottled, and cooled. Salt is a standard ingredient, but there's no brine fermentation. Other ingredients include corn syrup or other sweeteners, onion powder, and distilled vinegar (the modern replacement for the more time-consuming natural pickling process).

Sugar-sweetened organic Heinz ketchup beat out the more commonly available high fructose corn syrup-sweetened version in our ketchup taste test, and it's worth noting that ketchup generally has a very high sugar content —about 22 grams per hundred, according to the USDA. That's something to be aware of both when buying and using it. Reduced sugar ketchups are also available, but those contain artificial sweeteners such as sucralose.

You might also look at the tomato content, as different grades of ketchup are available, and the ketchups with the highest tomato content are graded "fancy." However, our taste test found that stronger tomato flavor didn't necessarily mean a better ketchup. Good ketchup strikes the right balance of sweet, salt, and acidic flavors.

Homemade ketchup recipes (like ours) follow a similar course to commercial recipes, though the home cook can add some depth of flavor by roasting the tomatoes before blending them. Yet for many the idea of making ketchup seems absurd. Consumers want the ketchup flavor they're used to, and that means ketchup from a bottle. In our test, Heinz ketchups took the first and second spots thanks to their tart, familiar flavor.

Some products that come in both plastic and glass bottles use slightly different ingredients for the plastic version to make them more easily squeezable. That's not typically necessary for ketchup thanks to its unusual material qualities. Ketchup is a thixotropic or "non-Newtonian" liquid. That means it becomes less viscous as it moves—the more you shake it, the easier it flows. That's why ketchup stubbornly stays in a glass bottle at first and second shake, and eventually rushes out all at once to say hello. That's also why you're better off with a squeezy bottle. (Heinz now only sells ketchup in glass bottles to restaurants.)

Because ketchup has a high acid content, it's shelf-stable, but it should be stored in a cool, dark place to keep it safe and tasty, and manufacturers recommend refrigeration.

We all know what ketchup is for—burgers and fries, and maybe hot dogs (though never in Chicago)—but it's also a versatile cooking ingredient. It can be used as part of a glaze for meatloaf, meatballs, ham, or pork chops, to help keep them moist. It's a key addition to a sweet-style barbecue sauce, providing a tangy flavor to pulled pork. It's a utility player in a lot of simple dipping sauces, and also used in some recipes for pad thai and sweet and sour sauce.

Ketchup and mayonnaise work wonders together. They're the key ingredients in Thousand Island dressing, Russian dressing, and Marie Rose sauce, and they combine beautifully in both Utah's own fry sauce (one part ketchup to two parts mayo), and In-N-Out Burger's famous proprietary "spread." You can't make an Animal-Style burger without it! (Or a homemade approximation.)

Tomato now reigns supreme in the world of ketchup, to the extent that the U.S. FDA actually defines ketchup as a food prepared from "tomato ingredients." Yet you can still find other types of ketchup on the shelves, such as mango ketchup, pear ketchup, and even a modern version of mushroom ketchup.

Most of these follow the sugar-and-vinegar-based recipe of tomato ketchup, rather than the brine-based recipe of original "ke-tsiap." Banana ketchup, for example, was created in the Philippines during World War II because of the limited availability of tomatoes. Ketchup may never stop evolving, yet we suspect that tomato ketchup is the one you'll always come home to!

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