Tā zuòshì xǐhuān páogēn-wèndǐ, nòng qīngchǔ měi yī gè xìjié.
He likes to get to the root of things and clarify every detail.
Tips
memory
刨 (to dig up) + 根 (root) + 问 (to ask) + 底 (bottom), literally 'dig up the root and ask about the bottom.' A vivid image of someone relentlessly excavating the truth.