Got to love Mr. Bayless' take on Mexican cuisine. There have been others (Kennedy and Trilling come to mind) who have tried to incorporate it's cuisine into the American vernacular but Rick has the "Julia Child" touch for my way of thinking. He makes the "mysterious" knowable and delineates the differences between Tex-Mex and Mexican cuisines in easy
steps.
I liked his 'Mexico One Plate at a Time' to start learning about Mexican cuisine and ingredients, then moved on to 'Authentic Mexico', which truly travels through the various regions of Mexican cookery.
I'd say take your pick based on where DW is in her interest. Or get her both books;).