Here's which Chipotle ingredients are prepared fresh in restaurants

Chipotle prepares most of its menu items by hand.

Several ingredients, including the onions, lettuce and cilantro, are chopped by hand, while others - such as the tomatoes - are chopped using food processors, according to the Wall Street Journal.

The company once tried using a processor for the onions, but the machine left the onions watery and soft, so employees returned to hand chopping, according to the report.

Chipotle also once used tomatoes that were diced at a central kitchen and shipped to restaurants in plastic bags, the report says. The company stopped using those tomatoes last year, and installed dicing machines in its restaurants to instead chop tomatoes on site.

Because of all the precise hand-chopping that Chipotle requires, the food preparation takes a lot of time.

Employees spend about four hours every morning chopping and prepping ingredients ahead of the lunch hour, according to the Journal.

The tortilla chips, rice and guacamole are among the items that are hand-made in restaurants.

Here's an employee making tortilla chips:

Other foods, such as the carnitas and barbacoa, are prepared in a central kitchen and shipped to restaurants in plastic bags. Then the bags are heated in water and the meat is hand-shredded.

The chicken, on the other hand, is diced and cooked in restaurants.