Minimalist Intervention is a term invented by Dr. James Wilk, to describe a small nudge that brings about the desired change, quickly, with minimum effort and with existing resources.
A minimalist intervention is like turning the tube of a kaleidoscope a fraction so that the old pattern disappears, a radically new pattern replaces it, and the old pattern cannot be recovered. There is no gradual change from the old pattern to the new. The change is instantaneous.
According to Dr. Wilk, even the most intractable or complex problem can be dissolved easily and permanently with a minimalist intervention.
Martin Leith uses the term SABRE intervention (a Small Action that triggers a Big REsult) to describe a similar kind of intervention.