(Crain's) — After years of a relatively unchanged menu, Chipotle Mexican Grill Inc. has added soup to its menu.

Chicago-area restaurants, which handed out free samples of posole soup over the past week, launched the item Monday. The chain's home market — Denver — is the only other market to have the new item, says Chairman and Co-CEO Steve Ells.

"We think Chicago is a great market," he said in an interview Tuesday. "I love posole. It's a great cold-weather addition to the menu."

Chipotle's posole is a vegan soup — made without any animal products — with a tomato and hominy base, vegetables, and seasoned with spices like cumin and fresh herbs like oregano.

An 8-ounce portion sells for $3.33; it can be garnished with chicken for $4.70.

"We’ve had a lot of interest from customers in our web comments," Mr. Ells said. "They (were) interested in a soup, so we’re going to give it a try there and see how it does."

Further embellishments could turn it into a chicken posole bowl with rice, meat and chips for $5.53, Mr. Ells said.

Denver-based Chipotle’s last new menu addition was salads more than three years ago.

At the company’s Oct. 21 third-quarter earnings call, Mr. Ells said that it was putting soup in a couple of markets on a limited basis during the fall. He also said the company was testing breakfast tacos and burritos at the Washington, D.C.-area Dulles International Airport.

The 18-year-old chain, which gained national scale under former owner McDonald’s Corp., has been considering other menu changes, including a kids menu.