Okay, so you have an interview. So they already think you're smart. So don't spend the interview proving you're smart. Spend the interview modeling what it would be like with you as a colleague.
This performance should be much more like talking with your Ph.D. colleagues at a writing workshop, than either teaching or talking to your adviser.
Don't talk up, don't talk down. Talk to equals.
Do you have your ikebana sentences? You will need them. The most pocket sized, accessible version possible.