This one phrase may capture the essence of being an associate leader more than any other.  Here’s why:

Being an associate leader of any kind means having to spend some of your time following and some of your time leading.  For the most part, that means having to develop two different but overlapping sets of skills.  This question sits right at the point of overlap between the two.

As a follower, one (probably unwritten) element of your role is to be a sounding board for your leader. If your Lead Pastor is a visionary, there’s a good chance that at some point he or she will come to you overflowing with thoughts and ideas.  When you find yourself in that situation, your leader is best served if you are an expert question asker.  You might be able to begin with questions like “How does this tie into our mission?” or “What would be your driving purpose in doing this?”   Give the Lead Pastor plenty of time and space to talk out his or her ideas.  

Then, when the conversation is drawing to a close, use this question to transition from ideas to action: “What do you need from me?”  This gives you a chance to participate in the new idea while clarifying any new expectations.  In many cases, by clarifying which piece of the project is yours, it will also ensure that the whole project doesn’t end up accidentally on your plate without you knowing.  

On the leadership side, this can be a powerful question as well.  Parishioners test the safety and dependability of their pastors with moments of vulnerability.  The pastor’s instinct can be to offer advice and solutions but this can frequently shut the conversation down.  A question, on the other hand, invites further conversation.  The question “What do you need?” empowers the parishioner themselves to lead themselves.  
It’s important to note one difference between asking this question with a Lead Pastor and a parishioner.  With a Lead Pastor you are asking what he needs from you.  With a parishioner you are asking more generally what he needs.  Don’t be quick to meet those needs yourself.  Rather, ask a follow up question: “How can you get those needs met?”  Again, this empowers the parishioner rather than creating dependence upon you as a pastor.