The butter not only adds richness to the burger and prevents it from drying out, but it also butters the bun for you. We're not going to downplay it, these burgers are decadent. But, if you're going to eat a burger, you may as well do it right. And, this recipe does it so right.
The word persistence means the quality of being determined to do or achieve something. It's tenacity. It means firmness of purpose. It is a continuing, repeating or lasting of something. Use the link and read a few similar definitions.
1. : the quality that allows someone to continue doing something or trying to do something even though it is difficult or opposed by other people. He admired her dogged persistence in pursuing the job. His persistence in asking for a raise was finally rewarded.She has shown a lot of persistence. the quality that allows someone to continue doing something or trying to do something even though it is difficult or opposed by other people.