Pour both ingredients into a mixing glass filled with ice. Stir, and strain into an old fashioned glass filled with fresh ice. (This recipe renders a fairly dry version of the drink. You can use more Kahlúa and less vodka to make a sweeter version.)
Recipe by the modern barista at https://themodernbarista.com/index.php/2015/12/23/homemade-kahlua-using-starbucks-via/