My favorite Agile technique is "Take the problem to the team." Though I first learned about this technique over thirty years ago in IBM New Manager School where it was called "Give it [the problem] to the team," it was only after hearing Lyssa Adkins speak at an Agile event and subsequently reading her book "Coaching Agile Teams" that I was able to rekindle that long lost management training into an actionable, everyday use skill.
The premise of "Take the problem to the team" is that the resolution or solution to a problem is the team's commitment, not yours. Hence, when we solve a problem for the team (often when they might not even realize there is a problem), we are in essence inflicting our help upon them and asking them to commit to what we have decided.
Though a simple concept, the idea of not taking charge of things and solving a problem for the team goes against the ingrained behavior of many managers. I know it does for me.
Naturally, there is a context for practical application, but generally speaking I have found this to be one of the most useful and perhaps my favorite Agile technique. What's yours..?