This is learning small snippets or phrases rather than just vocabulary or whole sentences.
German with Anja is releasing 3 videos on the technique, the first two are available so far. Here is the first:
It seems to me that the Rocket German course is a good source of the chunks. Levels 2 and 3 of Rocket German do present you with quite a few long sentences and I never found learning these whole sentences particularly useful, but breaking them down into useful chunks looks like a good idea.