It's such a simple thing, the burrito. Take some rice and beans, some meat, a little salsa, spread it on a soft tortilla, fold and go. It's the ultimate convenience food, was in the vanguard of the Mexican-cuisine invasion that changed the way our entire country eats, and still stands shoulder-to-shoulder with the dumpling, the cheeseburger, foie gras and cassoulet in the pantheon of mankind's great food innovations. Although the burrito is now served in wondrous variety at hundreds of restaurants across the city, Chipotle takes the prize for its constant improvement of what started life as the best burrito in town and now has become the best burrito on the planet. From free-range Niman Ranch meats to organic beans, fluffy rice that's perfect no matter what hour you arrive, chewy tortillas heated to order, three distinct salsas and great guac made fresh all day, this Denver creation born out of the newfangled ideas and dedication of hometown boy and former line cook Steve Ells does everything right. True, Chipotle is now a McDonald's brand. And yes, what began as a simple University of Denver-area taquería has been transformed into one of the fastest-growing, most pervasive chains in the country. But you know what? Sometimes success comes to those who actually deserve it.