In seeking to measure the “true” cost of a plate of food around the world, we have discarded nominal prices: when incomes are as polarized as they are, these tell us little. Instead, we have measured the proportion of daily income that a person in a developing or conflict-stricken country might spend on a basic plate of food. We then retro-projected this ratio onto the income of a developed-nation citizen, such as a resident of New York State. So that while a New Yorker might expect to spend just 0.6 percent of their daily income on the ingredients to make a simple 600 kilocalorie bean stew, someone in South Sudan would need to spend as much as 155 percent of their income. Or, to approach it from the other end, it would be as if a resident of the Empire State were to pay US$321 for their stew.

https://docs.wfp.org/api/documents/WFP-0000023327/download/?_ga=2.49155558.1106312969.1508148290-383879953.1508148290