Basically, what she does is ask a character a question, one that you might hear in an interview. Then she writes the answer from her character's point of view. For her, the answer is usually pages long. (By the way, if you have the chance, you should definitely go check out that post! It's a lot better at talking about this process- after all, it is the original! :-) Now, for me, the answers are typically shorter. I also have a tendency to ask more of the "quick answer" type questions, like "beach or mountains?" and "dog or cat?"
I also like taking personality tests for my characters. Answering those questions helps me get a feel for their personality, and what types of things they like and don't like. Also, the answer, if I agree with it, can give me a good, quick archetype to refer to. Another thing that helps with these is when the answer you get is something that you feel doesn't quite fit your character because then you start thinking about why it doesn't fit and how your character is different.
For a short story I just started writing, I didn't know anything about my main character other than the fact that she was the daughter of an inventor and a journalist. So I decided to start interviewing her. Once I started answering the questions from her point of view, her personality came to life. It helped a ton!
And now I'm off to go take personality tests for that character! :D