Describe a person who taught you a new skill

I'd like to talk about Khoa, the shift leader at a small café on Trương Công Định Street in Đà Lạt, where I worked part-time during my second year at university. The skill he taught me was latte art, which sounds trivial until you've poured forty cups in a row and every single one looks like a melted ghost. Khoa was only two years older than me, but he'd been behind an espresso machine since he was seventeen. His method was surprisingly strict. For the first week he wouldn't let me touch milk at all; I practised with water and a drop of dish soap, because it foams in a similar way and costs nothing. He'd stand beside me and say, 'Don't watch the jug, watch the surface.' Then he filmed my hands on his phone and played it back in slow motion so I could see exactly where my wrist went wrong. It took about three weeks before I produced a heart that a customer could recognise without being told what it was. What I appreciated most was that he never took over. Plenty of people grab the jug and show you again, but he'd just wait, even when the queue was getting long and the owner was glaring at us. I felt genuinely grateful, and a little embarrassed at how proud I was of a shape in a cup of coffee. I left that job over a year ago, but I still make a decent tulip at home, and more importantly I borrowed his approach: when I tutor my younger cousin in maths now, I keep my hands off the pen and let her get it wrong first.