Shocking, but true: Some 25 years ago, Galatoire’s Restaurant in New Orleans did not offer a crawfish dish.

“It was Cajun,” said David Gooch, whose family has operated the Bourbon Street eatery for more than a century. “New Orleans food was French Creole only.”

But the twain finally met when Nelson Marcotte devised an edible argument to elevate the beloved fare of his native bayou country to the menu of one of the Crescent City’s most traditional and revered establishments.

A waiter at Galatoire’s, Marcotte prepared a batch of crawfish étouffée for his employer.

“It was buttery and delicious,” recalled Gooch.

And that is how the simple, satisfying dish went from backwater to big city, from indelicate to delicacy.

Invented 70 or so years ago beside the Bayou Teche in Breaux Bridge, La. — some 125 miles west of New Orleans — crawfish étouffée has been declared the “most ordered” item in Cajun Country restaurants by chef Paul Prudhomme.

Every Cajun family has its own version, but the essence of étouffée is crawfish, butter and onions, said Barry Ancelet, professor of Cajun French and folklore at the University of Louisiana, Lafayette.

A smaller, less showy cousin of the lobster, crawfish has had to claw its way to culinary respect. Sometimes called crawdads, crayfish or mud bugs, the crustaceans inhabit southern Louisiana’s flooded rice fields, swampy lowlands and even backyards.

Slaves first used them as a protein source, boiling them in tangy seasonings, according to Dickie Breaux, owner of Café des Amis in Breaux Bridge.

Later, white subsistence farmers added crawfish to their diets.

But the Cajuns who farmed and fished along the Atchafalaya Basin swamp rarely mentioned to outsiders that they ate crawfish.

“It was considered lowly fare. It was ‘those Cajuns eating their mud bugs,’ ” Breaux said.

Crawfish would be served to family but never at a restaurant, he added.

That changed sometime in the early 1930s when the Hebert sisters of Breaux Bridge cooked up the first étouffée for guests at their inn.

Mud bugs or no, patrons spread the word as far away as Texas that the dish — which the sisters called crawfish court bouillon — was delicious.

The Heberts sold their establishment and recipe to Ilene Champagne, who renamed it by accident. A French-speaking patron asked Champagne what she was cooking and she replied in French that she was smothering crawfish.

Étouffée (pronounced ay-too-fay) is French for smothered. The name stuck, Breaux said.

Cajuns themselves rarely tasted the dish, Breaux pointed out, because they had no reason to patronize the inn.

But after World War II, Thelma Breaux, no relation to Dickie Breaux, offered her version of étouffée in a little diner at her husband’s gas station along the two-lane road leading out of town.

The men who bought Thelma’s étouffée for 50 cents a plate told their wives about their favorite lunch. Soon, Cajun women were creating their own take on étouffée.

Everyone soon realized that, with a dish so simple, the addicting flavor came from the peppery seasonings and the crawfish “fat.” In Cajun groceries, the so-called fat was sold beside the crawfish tails in a little paper container like the one used for small servings of ice cream, Breaux recalled.

What passed for fat was, in fact, the creature’s liver. Sometime in the 1960s, public health authorities discovered that it was a breeding ground for bacteria and ordered it removed from the market.

That was a dark day, if you ask Breaux. Ever since, he said, cooks have tried to recapture that flavor.

Some have added to the mix cream of mushroom soup, an ingredient that makes étouffée purists like Ancelet cringe.

“The minute you add mushroom soup, you aren’t making étouffée. It might taste good, but it’s not authentic,” he declared.

Another variation on the original does not sit well with Breaux. Ask him if one should ever add tomatoes to the dish and he recoils, “Oh, heavens, no.”

As someone who has actually tasted Thelma Breaux’s recipe, Breaux added seafood stock to the recipe served at his bayou country cafe to achieve a comparable flavor.

He confirms Prudhomme’s declaration. Étouffée is the most ordered dish at his restaurant, whether served by itself or ladled over eggs or eggplant.

Despite its humble start, crawfish étouffée was destined to be served on the white tablecloths of some of America’s finest restaurants.

“The dish is elegant in its very simplicity,” he said.