Keys to Good Cooking: A Guide to Making the Best of Foods and Recipes by Harold McGee
McGee is a food scientist and a columnist for the New York Times and author of the best general food science book ever (above).
This book is a (mostly successful) attempt to cover this academic subject in user-friendly fashion. McGee has a great ability to boil down a complex idea to very few words and bring clarity to the subject.
The book is designed so readers can just dive in anywhere, so he often repeats things, almost word for word, from chapter to chapter. Lots of great tips. Penguin, 2010, 576 pages, hardcover, few recipes, few illustrations.