As a kid I used to love lengua but I didn't know what it was. Then when I was old enough to know I didn't eat it for years because it was "gross". Then my mom snuck some in on me one time and I loved it. I'm over it now, I loves me some lengua.
We boil with herbs and spices sometimes with a jalapeno tossed in the water. After it's cooked we cube it and serve with corn tortillas, onion, cilantro and salsa. Make sure to remove the outer skin, I know a guy that didn't do that and well I'll just say he didn't enjoy his dinner very much.
Also, after it's cooked and cubed we sometimes fry in a skillet with onions until browned. Bon Appetite!