Special equipment: Single-cup Vietnamese-style coffee filter
Put the condensed milk into a coffee cup. Place the filter on top of the cup. Unscrew the filter, add the coffee grounds, and screw the filter back on. Pour in enough boiling water to fill the filter. Close the lid and let the coffee slowly drip into the cup. Remove the filter and stir the coffee and milk together. Pour the coffee mixture into a glass of ice and stir to chill. Serve.
Recipe courtesy of Anthony Nguyen, Saigon Banh Mi So # 1, NYC