In an age of multinational food chains, demand for the 125-year-old dabbawalla delivery system is at an all-time high.

While traveling across Asia for its ongoing series on sustainable food, the team from Perennial Plate has covered agriculture, advocacy, cooking, and business. Now, Daniel Klein and Mirra Fine conclude their journey with an ode to the people in between -- those who deliver the food.

“Dabbawalla” comes from the term tiffin dabba, referring to a tiered lunch box and “walla,” a carrier or vendor. As Saritha Rai explains in The New York Times, India’s dabbawalla network originated during the British colonial occupation after cities were flooded with new, regional workers as a way to bridge the distance [both literally and figuratively] between their work sites and their homes. Each morning, after the recipient has gone to work, family members who remain at home (mothers, wives, grandmothers, and sisters) prepare a freshly-cooked meal to be picked up by a dabbawalla, sorted and distributed at railway stations, and hand-delivered to their loved one at the office.

Today, Mumbai is home to approximately 4,000 dabbawallas who deliver tens of thousands of lunches via an intricate, 125-year-old coding system without fail. The dabbawallas rely on a series of codes written on the sides of the boxes that function as directions. Though many of them are illiterate, they have learned to sign their names on the receipt. In fact, the delivery service is estimated to have an error rate of 1 in every 16 million transactions, and has been studied by corporations like GE for its precision and accuracy.

Despite the influx of food chains and eateries in Mumbai over the last decade, demand for the lunchtime service is higher than ever before, with customers from multinational corporations and hedge funds. Now, clients can put in a request via text message or e-mail. Variations on the service are even cropping up in cities across the United States with heavy South Asian populations, like San Francisco and New York.

For more from the Perennial Plate, visit their site.