Irvine-based In-N-Out Burger is the target of a petition that demands the fast-food burger institution add a meat-free meal to its menu.

Launched last week on change.org, the petition by Washington D.C.-based Good Food Institute said the burger chain has been “letting its fans down by failing to serve anything that would satisfy a burger-loving customer who wants a healthy, humane, and sustainable option.”

Good Food Institute is a fledgling nonprofit that supports the use of healthier and sustainable food supplies. It specifically supports a food supply that shifts away from animal agriculture.

Though the group faults In-N-Out for not offering a vegetarian option, most In-N-Out fans know that anyone can custom order a meat-free burger with cheese, essentially a grilled cheese sandwich.

A spokeswoman for Good Food said a “cheese slathered bun” is not a healthy solution for vegan eaters.

“I don’t think that satisfies people’s desire for a full entree,” Emily Byrd, a spokeswoman for Good Food Institute, said Monday in a phone interview.

The nonprofit said In-N-Out is the first restaurant Good Food has targeted since the group’s establishment earlier this year. She said the group focused on In-N-Out because it is a “cult favorite” with a large following, but small enough to easily add a meatless burger to its menu.

“As a company that prides itself on both customer satisfaction and ethical business practices, adding a meat-free option is a no-brainer,” the petition states. “And by making this single addition, In-N-Out would be making a huge statement that it truly cares about its customers health and the health of the planet.”

In-N-Out could not be reached for comment about the petition, which has reached more than 16,200 signatures as of Monday afternoon.

Byrd said the group plans to send the petition to In-N-Out President Lynsi Snyder once it reaches 25,000 signatures.

Contact the writer: nluna@ocregister.com