New Delhi, April 11 -- On most days in Bengaluru, Bert Mueller could pass unnoticed, except for the auto, which is bright red and unmistakable. Mueller, an American who moved to India in his early 20s, often drives the three-wheeler around Indiranagar, where he lives. Gifted by co-founder Gaelan Draper when he exited the company, it is the only vehicle Mueller owns.

More than a decade after he first arrived in India as a student, Mueller, 36, is the co-founder and CEO of California Burrito, a quick-service restaurant chain set up in 2012 that serves burritos, tacos, burrito bowls and quesadillas in a build-your-meal format (choose your base, your protein and toppings). One of the country's largest Mexican-inspired food chains, it has 130...