Welcome to the eGullet Recipe Cook-Off! Click here for the Cook-Off index. A couple of days ago, we were trying to figure out a good cook-off topic for late April/early May, and someone suggested tacos. Shortly thereafter, Mark Bittman of the New York Times decided to weigh in with this article, titled "Sunday Morning, Yucat√°n:" Bittman shares three recipes, as well, for Taco Filling With Poblano Strips and Potatoes, Mushroom Taco Filling, and Nopales Filling. Meanwhile, over at Bon Appetit, Ste