I learned this recipe in the Moneterrey, Mexico kitchen of one of the most gracious ladies I ever met. She didn't speak a word of English and my Spanish was sketchey at best. Yet she still let me get in her way as she cooked. I learned the recipe without the potatoes, but having eaten steak & potato tacos before, I knew I could "authentically" stretch this dish by including them. In fact, I like the dish with the added potatoes so much, I have only prepared it once without the potatoes.