Steve Ells broke all the rules when he opened his first Chipotle Mexican Grill 20 years ago in Denver. The company's founder insisted on using fresh, high quality and sustainable ingredients. The chain now has close to 1,600 restaurants and serves nearly a million a day. Ells, who considers himself a chef first and a CEO second, talks to us about hiring the right people and making sure your customers get exactly what they want in this Learning from the Pros.