Umami accounts for good taste

Who would have guessed that a magazine advertisement could lead you on the path to enlightenment, but it happened to me. It was an ad for Kikkoman soy sauce mysteriously referring to the new "fifth taste," beyond sweet, sour, salty and bitter. They called it umami, and like the guy who hears the punch line but not the joke, I needed to know what all the fuss was about. The truth behind umami.

Up until the 19th century the consensus was that humans could detect four basic tastes. And this belief had been held for a few thousand years, all the way back to the Greek philosopher Democritus who not only identified the four categories of sweet, sour, salty and bitter, but assigned shapes to each taste. Things that were sweet had round, large atoms while things that were salty had particles of an angular shape. And that was it.

Then in the late 1800s, two men separated by thousands of miles were arriving at a new conclusion: There was more than just the four tastes. In Paris it was the promethean chef, Auguste Escoffier, who was revolutionizing the food scene by making food that actually tasted good. Previously haute cuisine had been all about presentation - carvings of tallow and everything draped in aspic - with flavor taking a back seat. One of Escoffier's secrets for deepening and elevating the flavors of his renowned cuisine was veal stock. Turns out that it's high in umami.

Meanwhile, over in Japan, chemist Kikunae Ikeda was pondering his bowl of dashi - a soup made from sea weed and a staple in their kitchens - and trying to put his finger on what made it so delicious. He determined that it was glutamic acid and named his new discovery, umami, loosely translated as "delicious" or "yummy."

The concept didn't really catch on because scientists had only identified the four receptors in our tongues. It wasn't until the year 2000 that a research group at Miami University determined that in fact we do have the receptors for a new category, and umami became the bona fide "fifth taste."

Umami can be found in just about any food that was once living - plant or animal. It's when and how the proteins break down that makes things tasty. Through fermentation as in soy sauce or wine. Through aging like in parmesan cheese. As a result of ripening like tomatoes or through cooking a steak or piece of fish. It is not as mysterious as Kikkoman made it sound, and that's the enlightening part. It's been there all along.

Today's recipe incorporates all of the above, and was hatched long before I knew of umami. Perhaps we don't need science to tell us what tastes good. Perhaps we need only to follow the path and enlighten up.

• Brian Shaw and his wife Ardie own Cafe Del Rio in Virginia City.

8 big ones

Filling:

2 pounds outside skirt steak*

1 cup salad oil

1 tablespoon minced garlic

1⁄3 cup soy sauce

Juice from 2 limes

1⁄4 cup rough chopped cilantro

Remove the skin and fat from the skirt steak, or better yet, have the butcher do it. Combine the marinade ingredients in a non-reactive bowl or pan, add the skirt steak and toss to coat. Cover and refrigerate overnight.

*If you can't find skirt, use flank steak.

Salsa:

11⁄2 pounds Portobello mushrooms*

1 medium yellow onion, peeled and sliced 1⁄4-inch thick

1 teaspoon minced garlic

2 tablespoons balsamic vinegar

3 tablespoons soy sauce

4 tablespoons olive oil

1 tablespoon chopped pickled jalapenos

4 medium roma tomatoes, cored and diced

2 tablespoons chopped cilantro

Remove the stems from the mushrooms and, using a spoon, scrape out the dark "gills" from the underside. Combine the garlic, soy sauce, vinegar and olive oil in a stainless steel or glass bowl and add the mushrooms one at a time making sure they each get coated with the marinade. Allow to sit for about an hour.

Remove the mushrooms from the marinade, reserving the marinade, and grill them on a hot charcoal or gas grill along with the onion slices. The mushrooms should be just soft but not blackened. Return the cooked onions and mushrooms to what's left of the marinade, cover and let cool. When cool, dice the mushrooms and onions, combine with the remaining ingredients and toss in the marinade bowl. Taste for salt and drizzle a little more olive oil if dry.

Grill the steak to your liking, and allow to rest for 10 minutes. Cut into 2-inch chunks, then, cutting against the grain, slice into thin strips.

*Crimini or domestic mushrooms will do, just a little harder to work with on the grill.

Assembly

8 flour or corn tortillas

shredded lettuce

crumbled Cotija or parmesan cheese

sour cream and limes for garnish

Warm the tortillas on the grill or wrapped in foil in the oven, and load 'em up.