NY Times has a column on Kenji’s recommendation for a butane torch as your essential took for getting “wok hei” in your stir-fry. I think the Comments are the most fun of all, LOL:
The Elements of Wok Hei, and How to Capture Them at Home
The elusive smoky flavors and aromas of stir-fry can be achieved in your home kitchen. J. Kenji López-Alt shows you how.
NY Times 04Sept2020