We know sweet, sour, salty, bitter, but many of us are less familiar with umami, that elusive fifth basic taste that was discovered by a Japanese scientist in the early twentieth-century and is only now gaining popularity stateside. What does it taste like? Think of umami as that savory quality in soy sauce, roasted meat, cooked tomatoes, and soy sauce. The best way to discover this world is with a burger. Believe it or not, the classic burger already hits all these primary flavors by getting sugar and umami from ketchup, sweet and sour from pickles, richness from the mayo, heat from mustard, and, of course, salt and still more umami from seasoned beef. The so-called "umami burger," showing up increasingly on restaurant menus and in next-gen fast food restaurants, turbocharges the classic by maintaining sacrosanct elements – bun and beef, tomato and lettuce – while using Asian flavors like kimchee, daikon, and soy sauce to crank up the volume everywhere else. The bottom line: The umami burger might be the most pleasurable dish man has ever created, and here are four ways to make one at home.