Othermore IRVINE, CALIFORNIA — As Taco Bell's CEO, Brian Niccol has been unable to fulfill what he says is his customers' No. 1 request: taco delivery.

"We still haven't figured out how to do it," Niccol told Business Insider.

Taco Bell could launch delivery today if it was willing to compromise on quality, Niccol said.

"Could we probably just go do it? Sure. But it would just be OK," Niccol said. "OK usually ends up in a slow death. You buy a shirt, and you're like, eh, it's OK. But slowly and surely it moves to the back of your closet with the tag still on it. And it never makes it out of the closet because you're like, eh, it's OK."

The Mexican chain's shortcoming isn't for lack of trying. Taco Bell has experimented with third parties, including DoorDash, but no one has managed to deliver the food quickly enough for the company's taste.

"The third party folks, the aggregators — they're just not fast enough," Niccol said.

Currently, Taco Bell is looking into building an in-house delivery program, using insights from sister brand Pizza Hut. More tests are likely on the horizon.

"I'd rather keep experimenting until we really believe we've got it right," Niccol said. "I think we've had the courage to say that's not right. That's just OK."