Tortillas. Meat. Cheese. Salsa. What’s so complicated about a quesadilla?

Plenty, for Chipotle Mexican Grill. The restaurant chain announced Thursday that it will add five new menu items — quesadillas, nachos, chocolate milkshakes, avocado tostadas and an updated salad — at its test kitchen in New York City, for eventual rollout nationwide.

But while most fast food companies introduce new products routinely to get people in the door, such changes are antithetical to the deliberately limited menu that built Chipotle into a $13 billion company.

New grills must be purchased. The assembly line must be re-choreographed. When those quesadillas finally hit the market, Chipotle simply must get them right. A string of food-borne illnesses and a crop of new restaurants have driven many of Chipotle’s customers toward its competitors, and now the company is retooling its menu to win them back.

Chipotle’s 2,500 stores aren’t set up to make foods that deviate wildly from the basic menu of burritos, bowls, salads and tacos. The grills, for instance, are designed to warm up tortillas in a few seconds. But they take two and a half minutes to cook a quesadilla, which some stores already offer as an off-menu item. That’s an eternity for a restaurant like Chipotle, which falls within the “quick-service” category that includes fast food and its slightly more upscale cousin, fast casual.