Quinoa-containing beverages and methods of processing and manufacture include mechanical grinding, milling or pulverization of natural quinoa seeds to produce a quinoa ingredient for a beverage. The process includes the steps of providing washed quinoa, milling quinoa to within a specified range of particle sizes, blending milled quinoa with a liquid base such as water, and heating the blended beverage to within a specified temperature range. Additional steps may include the introduction of other compatible ingredients, and roasting quinoa seeds prior to milling or grinding. Use of automated processing equipment for commercial scale beverage production is also described.