What’s old is new again —  at least on restaurant menus. Such back-to-basics ideas and ingredients as butchery, broths and butter are regaining popularity among consumers, who seek more authentic and simple options.

“Talk about a return to the good old days,” said Nancy Kruse, president of The Kruse Co., Atlanta, during a presentation at the National Restaurant Association Restaurant, Hotel-Motel Show held May 16-19 in Chicago. “The entire category of fats and oils has turned on its head. Many of you operators never left butter, but from the larger customer point of view, butter consumption has increased 24% since 2001.”

Ms. Kruse discussed profound changes in consumer attitudes and behavior that are affecting the restaurant industry. The confluence of three “mega-trends,” including ongoing economic uncertainty, a shift to technology as the basis of economy, and an unprecedented generational changeover, has created multiple disruptions for operators.

A new consumer mindset of “farm trumps factories” has emerged, with many diners demanding real, clean and authentic foods and many national chains, from Chipotle Mexican Grill to Chick-Fil-A, responding with major menu moves.

What’s old

The key to delivering on demand for simple and authentic foods is conveying freshness in product, preparation and presentation, Ms. Kruse said. Domino’s Pizza, White Castle, Papa Murphy’s and other chains have added open kitchens, allowing consumers a peek at the process, which in turn has led to double-digit increases in customer satisfaction and perception of food quality and service, Ms. Kruse said.

Other decor elements embraced by restaurant operators include cast-iron skillets, mason jars and reclaimed wood, creating visual cues of a return to simpler times.

In addition to butter, other formerly feared fats, including lard, beef tallow, duck fat and schmaltz, are gaining newfound appreciation. And the revival of butchery as an art isn’t limited to specialty shops. Outback Steakhouse has offered Butcher Cut steaks for a limited time. Offal also is getting more attention on menus.

“The American consumer in the mainstream has never eaten things like tripe, tongue, tendon or marrow,” Ms. Kruse said. “Bone marrow is the new black, in culinary terms, ladies and gentlemen.”

The trend may be rooted in sustainability, as chefs seek creative ways to use all of an animal to avoid waste.

Broth is heating up, too, with health-minded consumers drinking bone broth for protein and nutrient benefits. Such chains as Sweet Tomatoes, Souplantation and Panera Bread recently have added broth bowls to the menu.

As refined sugar becomes “a dietary demon,” Ms. Kruse said, restaurant beverages are becoming simpler, too. Chick-Fil-A, for example, touts its lemonade as made from scratch daily with only lemon juice, pure cane sugar and water.

To further push authenticity and simplicity, several restaurant chains are sharing the backstory behind menu items. Arby’s, for example, describes its Smokehouse Brisket as smoked for at least 13 hours in a pit smoker in Texas. Chili’s features such items as house-smoked chicken quesadillas and guacamole that is prepared at the customer’s table. Pizza Hut calls its hand-tossed pizza “one of a kind,” with blisters and bumps on the crust as proof the product was not mass-produced in a factory.

“Blisters say ‘authentic,’” Ms. Kruse said.

Because authenticity, simplicity and freshness lack standards of identity, operators have ample opportunities to convey these qualities on menus, Ms. Kruse said.

“Am I suggesting prepared ingredients or convenience foods have no future?” she said. “Absolutely not. They are going to continue to be mainstays of your kitchen. It’s what you do with them that will make all of the difference going forward.”

What’s new

Among hot new ingredients and flavors, truffles are trending in butter, cheeses and glazes, and ghost pepper is red-hot on mainstream menus. Popeyes, for example, recently introduced ghost pepper wings.

“It does speak to the broadening of the American palate and how much more adventurous in general your diners have become,” Ms. Kruse said.

Celery and celery root also are growing on menus, adding color and crunch to a variety of dishes.

“There have been food writers who have suggested celery is the new kale,” Ms. Kruse said.

Fig is big in savory items, like Gordon Biersch’s prosciutto and fig flatbread, and Carrabba’s Italian Grill’s prosciutto-wrapped pork tenderloin with a port wine and fig sauce.

“The fig growers are saying their hope is that figs become as ubiquitous or as common to American kitchens as the apple,” Ms. Kruse said.

Behind sriracha, the fastest-growing sandwich condiment, according to Datassential, is savory jelly or jam. Garlic tomato and habanero jams are served at 8oz Burger & Co. in Seattle, and Brio Tuscan Grille offers applewood bacon and tomato jam bruschetta.

Proteins gaining popularity in restaurants are duck and lamb, appearing in familiar formats to appeal to mass-market consumers.

“I know many of you have struggled over the last 12 to 18 months with high protein costs, particularly with regard to beef and pork, so that has driven a lot of you to look for alternatives,” Mr. Kruse said.

At Brick House Tavern + Tap in Chicago, duck wings are served with sriracha ranch, and duck confit appears in lettuce wraps with such ingredients as hoisin peanut sauce, napa cabbage, crispy wonton strips and cilantro.

Lamb is featured in a sandwich at Occidental Grill & Seafood in Washington, with goat cheese, local strawberry preserves, arugula and pickled ramps, “making it accessible and easy for the consumer to give it a try in this really handsome sandwich,” Ms. Kruse said.

Speaking of sandwiches, the hottest thing between sliced bread lately is the banh mi, Ms. Kruse said. The Vietnamese staple, typically served in a French baguette with pickled carrots and daikon and cilantro, appeared on the menu at Which Wich, a fast-casual sandwich concept that served pork and shrimp varieties for a limited time. Cosi offers a pork belly banh mi with daikon, carrots, cabbage, jalapeños and Asian ginger sauce.

“We talked about the unexpected presence of offal, of a variety meats,” Ms. Kruse said. “Here is a mass-market chain with their take on banh mi, and the star here is — I’m not saying ‘bacon,’ I’m saying ‘pork belly.’ Kudos to them.”