Test cook Dan Souza shows host Christopher Kimball how to make Mexican-Style Grilled Steak at home. Next, tasting expert Jack Bishop challenges Chris to a tasting of dark chocolate. Then, man on the street Doc Willoughby learns about tacos with chef Alex Stupak of Empellón Cocina. And finally, test cook Julia Collin Davison uncovers the secrets to the ultimate Shredded Beef Tacos.