The frothy top comes from theatrically pouring the tea between two cups held arm's length apart — the 'pulling' that gives it its name.
Teh tarik is a sweet, milky black tea vigorously poured back and forth between two vessels to build a thick foam and cool it to drinking temperature. It's made fresh at mamak stalls and kopitiams (coffee shops) across Malaysia, often by baristas who perform the pull as street theater.