Performing just one task at a time, perfectly. The task has been pre-prioritized, initiated with triggers (queues) to re-engage it at a later time if dropped, and performed without distractions and with proper resources. The task falls under the umbrella of "what do I want."
You are powertasking when you have prioritized all tasks on your plate and begin, one task at a time, with the first priority task. As you switch off the task, you create task triggers or queues that allow you to re-engage the task with little effort later. The "switch to" task is in line again with your powertasking priorities list pre-developed before the task switch.