Wish I could give 10 up votes to this comment! Gran Cocina Latina is my bible in the kitchen. I love Latin American cuisine from Central to South America and parts of the southwest US where there is a large Latino population. This cookbook as it all. I've given this cookbook as a gift to at least 4 friends and they love it as well.
The other comments have covered Mexican cooking, but if you want a resource for Latin America in gerenal, Gran Cocina Latina. It's huge, useful, and shows you just how varied Latino cooking can get.
While it isn't exclusively South American, https://www.amazon.com/Gran-Cocina-Latina-Latin-America/dp/0393050696 covers South America (as well as Central America and the Caribbean and Mexico). Nice book. I haven't cooked from it yet.
For Brazilian, I've cooked from https://www.amazon.com/Brazil-Culinary-Journey-Hippocrene-Cookbook-ebook/dp/B0030P1WBI/ with tasty success.
Gran Cocina Latina: the Food of Latin America - My favorite cookbook by far!
The first thing I thought of when contemplating what to make for Herbs week was chimichurri. I went with the recipe from Gran Cocina Latina (special thanks to my parents for their ENORMOUS supply of cookbooks that I can pick through). After reading about it, I decided to go with it and that I would play with my new smoker as an added bonus. I rubbed a big slab of top round with garlic, salt and pepper and smoked it for 4 hours or so. I also served the chimichurri with some grilled strip steaks with the same rub and it was excellent with both types of beef. I would probably go with grilled over smoked in the future because the smoky flavor gets pretty overwhelmed by the powerful chimichurri taste. We served this at a party and went through 3.5 pounds of the beef on top of the dozen brats we also grilled. People couldn't stop eating it, just standing in the kitchen and dipping steak into the sauce.
Because chimichurri is so associated with Argentina, I wanted this week's cocktail to have some sort of connection with Argentina. I couldn't find anything until I remembered that Malbec is a big thing down there. I used this recipe for Burnt Sage Sangria using a bottle of Argentine Malbec. Because we were serving to guests, I wanted to something cool with the presentation. I had extra blackberries and so I froze one into each ice cube and used them in the sangria, which you can see in the picture.