Over the years, Reeves has, with his customary charm/ennui, set up a fun-poking mock argument between himself and newfangled critics about his copious use of Velveeta and YELLOW corn tortilla in “Mastering Nachos.” This has the effect of acknowledging the decline of Mexican cooking in American homes but blaming diet-consciousness for it. The real reason is that “Mastering” is too labor-intensive. It is about physically transforming meat and vegetables and spices by elaborately cutting and reassembling them, and chemically transforming cheese (or okay, cheese products) by whipping and emulsifying and baking them.