The combined influence of better-burger restaurants and the fast-casual customization model has had a profound impact on what burger brands now offer consumers. A recent survey by Chicago-based technology and services company Food Genius, which measures menu mentions at restaurant across the U.S., shows that while traditional ingredients like onions, tomatoes, and mushrooms are still the most popular topping options, more unique foods are taking root at burger concepts across the country.

According to Food Genius’s “Flipping the Burger: Menu Trends and Insights” report, peppers appeared on 25 percent of burgers, a percentage point above pickles, while avocado (8 percent), aioli (5 percent), and salsa (4 percent) broke into the list of top 14 toppings. Three quarters of all burgers include at least one type of vegetable, while 50 percent come with a sauce.

Eli Rosenberg, vice president of marketing for Food Genius, says the fact that peppers landed a point higher than pickles was the biggest eye-opener stemming from the report.

“What that tells us is that restaurants are not describing the standard lettuce, tomatoes, onions, and pickles,” he says, “and maybe there are some opportunities either for places that don’t use peppers in the menu items or places to call out or try new things with the pickle.”

Josh Lorence, COO of Florida-based BurgerFi, says that while burgers have been an American favorite for generations, customers today are seeking a more premium product, which extends beyond the quality of the beef.

“Typically with traditional [quick-service] restaurants, customization is not an option other than by removing the toppings that already come on the burger,” Lorence says. “Customers are looking to be able to build their own burger with some unique toppings, and that way they get to be creative and have more variety within the standard menu selections. They can always change it up, so when they come and visit, they can order a burger that will satisfy whatever their tastes buds desire each and every time.”

At BurgerFi, customers can choose from among more than 25 different toppings when building their own burger. While bacon is its popular premium topping, the concept offers everything from onion rings to hash browns and Peter Luger steak sauce as options to go between the buns.

Alternative meat options are also taking root at burger concepts. BurgerFi has its VeggieFi Burger, which is made of quinoa, lentils, fresh carrots, and zucchini, among other ingredients. Meanwhile, Burger 21 features a Spicy Thai Shrimp Burger, Larkburger serves a Truffle Burger, and Smashburger’s Michigan specialty option is an Olive Burger. Chicken burgers are also popular with many of these brands.

The increased variety on burger menus also extends into signature or secret sauces and the types of buns holding all of the premium ingredients together. “A lot of chains now are really looking for variations in burger carriers,” says Angela Burke, associate director of client services and marketing for Food Genius. “You'll see that in what Wendy’s has been doing, like the pretzel bun and the Ciabatta Bacon Cheeseburger. They’re looking for something beyond that traditional hamburger bun.”

“I think being food-forward and having the ability to customize your food with things that are on trend is really important,” says Tom Ryan, founder and chief concept officer of Smashburger. “I think we’re one of the only burger concepts that uses goat cheese. We have several recipes that use freshly sliced avocado instead of guacamole. [We have] everything from chipotle buns to brioche to potato buns in Idaho. We customize all those things and tailor them into the market in an industry-leading way.”

Larkburger cofounder and executive chef Thomas Salamunovich, who has worked in fine-dining restaurants throughout Europe and the U.S. for more than 30 years, developed his Colorado–based fast casual around the bar burger served at his popular Larkspur restaurant in Vail. Truffle–based toppings are a signature at Larkspur, and find their way to Larkburger, as well.

“We use truffle salt, a truffle purée, and a mushroom purée that we make as well,” Salamunovich says. “We have truffle french fries. [Due to cost,] we can’t buy whole, fresh [truffles] for Larkburger, but we use some of the byproducts and peelings.

“Our flavor profile is not based on sugar,” Salamunovich adds. “It is not sweet and tart, meaning it’s not pickle, relish, and ketchup-based, which so many are. This is much more of a traditional steak au poivre. The flavor profile is pepper, mustard, and beef. … It’s all real food. In some ways, one of the esoteric ingredients is the fact that we use real ingredients. We use raw product.”

Burger 21 seeks to appeal to both gourmet and traditional burger lovers. “The idea is to take chef-inspired recipes, create burger creations that the consumer couldn’t easily make at home, and give them that gourmet profile without the gourmet price tag,” says Dan Stone, vice president of franchise development for Front Burner Brands, which owns Burger 21.

Eleven of its 21 burgers fit into four non-beef categories: seafood, veggie, chicken, and turkey. Stone says 25 percent of all burgers the brand sells are non-beef.

“Sixteen items on our menu are beef, and 56 percent of our revenues on the menus are coming from non-beef items,” he says. “I think that says a lot for the demand for a fast-casual, high-quality experience.” Burger 21’s sauce bar offers 10 choices for its sweet potato and skinny fries, six of which come from proprietary homemade recipes, including an apple cider sauce and a toasted marshmallow sauce.

Despite all of the premium ingredients finding their way to burger menus, Food Genius’s Rosenberg says, operators should know that there is still room for the traditional toppings. Operators might just want to consider how they are listed on menuboard, he says.

“I believe there might be opportunities for other types of call-out around lettuce, onion, or tomato for people to have more variation,” Rosenberg says. “It’s really about differentiating yourself with your menu description, so that will move across the other attributes of the burgers, the buns, and toppings. I think things will get more descriptive.”