Jack in the Box's Portobello mushroom burger. Courtesy of the company
Jack in the Box’s Portobello mushroom burger. Courtesy of the company

In another sign of change in the fast-food world, San Diego’s Jack in the Box chain announced Thursday it is offering Portobello mushrooms on its hamburgers.

The latest gourmet burger features Portobello mushrooms, creamy peppercorn mayo, grilled onions, Swiss cheese and melted garlic herb butter on a quarter-pound sbeef patty

“The Portobello Mushroom Buttery Jack is a tasty addition to our Buttery Jack line,” said Iwona Alter, Jack in the Box’s vice president of menu strategy & innovation. “The Portobello mushrooms add a rich layer of flavor that we hope our guests will love and crave throughout the summer and into fall.”

The new burger is available now for a limited time at participating Jack in the Box restaurants.

Jack in the Box is one of the nation’s largest hamburger chains, with more than 2,200 restaurants in 21 states and Guam.

Chris Jennewein is founder and senior editor of Times of San Diego.