English is a second language to me, and I dutifully learnt 38 years ago that most verbs are turned into questions require the auxiliary to do: ‘Where do you live?’ rather than the Shakespearean-sounding ‘Where live you?’ But this is not not true for to be: ‘Where are you?’ is fine.
Having recovered from my astonishment, I tried to analyse the sentence. The ‘logical’ alternative would of course be, ‘How are you a good person?’ But I can see why the writer shouldn’t want to put it that way. Unless I’m much mistaken, it sounds pretty offensive, suggesting as it does that the other person is everything but a good person. That was not what this writer meant. She just wanted to ask, ‘How do you go about being a good person?’, ‘What are you to do so as to be a good person?’
So I think that in her ‘how do you be’, be was sort of shorthand for ‘get to be’, ‘become’, ‘act so as to be’, all of which do require the auxiliary verb to do in questions. Usually to be and its other forms (am, were, etc.) are just an inconspicuous glue, connecting the subject to some adjective, noun or both: the turtle is slow, a turtle is an animal, turtles are slow animals. In this case, however, it had a much stronger, ‘pregnant’, meaning. That’s why it behaved like one of those normal verbs with strong meanings, like to act, to wallow, to dehydrate and thousands more. Or so I think.
Which made me wonder if I could come up with an example of my own. Here then is another sentence where a form of to be has a different, but similarly pregnant meaning: ‘A wise person doesn’t do much, a wise person just is.’ I believe, or perhaps I just hope, that if I turned the latter phrase into a question, it would be okay to say, ‘Does a wise person just be?’
But as ever, that’s for native speakers to decide. Feel free to let me know!