It's easy. Lots of marinade recipes online. I don't always use Korean pear but I do use soy, ginger, garlic, sesame seed oil, sesame seeds, and sliced green onion.
This time I used shoulder steak which I tenderized with a mallet and to thin it out instead of having to thinly cut before marinating. I've done thinly sliced ribeye but this was also pretty good and much cheaper. Ribeye prices have gone insane. I couldn't justify 12/lb for something that thinly sliced. I'd use the shoulder steak again. I did cut out any veins of connective tissue though when I sliced it up. I do like 2" but thin squares to make em easy to wrap in the bib lettuce. A plethora of dipping sauces is what makes that meal so fun. We had sriracha, a Thai chili paste, sweet chili (Mae ploy) and some yum yum for the kids.