All right, sorry for the delay in answering your question Steve!
I'll go on a rant on cookbooks first. I don't like cookbooks that don't educate. Nearly all cookbooks are like that - they are mere collections of recipes. When I develop a recipe, I do research and have to make decisions what to include, what to omit, how much heat I am going to expose it to, and for how long, and using what method. Example - my bolognaise sauce uses chorizo instead of pepperoni. I use it because I like the smokiness and the depth of the paprika, but it is decidedly not traditional. If you deviate from a traditional recipe like this, you should state the traditional recipe and explain why you have deviated from it.
I also do not like books which take shortcuts. Example:
Jamie Oliver 30 minute meals. I understand there is a market for books like these for people who are too busy to cook, but when there are recipes that
direct you to use self raising flour in pizza I think it goes too far. That recipe does not even warn you what will happen if you follow that misguided recipe. You will get a cake-like crumb (instead of a bread-like crumb). SR flour is blasphemy against pizza.
Neither do I like books which are not precise. Examples - ingredients are specified by volume instead of weight, and you are directed to cook to time instead of temperature. Both of these are subject to huge variables - a "cup" of flour might contain more or less flour depending on how much it was compacted or whether it was sifted, a "stick" of butter means different things in different countries. "Four minutes on the pan" will give you different results if you are using a copper pan vs. stainless steel, gas vs. induction, ambient room temperature, your altitude, etc. It is far better if they were to tell you how to monitor your cook - e.g. "cook until 55C" or "fry until the onions turn translucent". Above all, the greatest insight you can gain as a cook is to understand how much heat to apply and for how long; and the best way to achieve this understanding is to start measuring the temperature of your food.
Of course, it should be no surprise that most cookbooks are like this. After all, nearly every cookbook written by a celebrity chef was probably written by a ghost writer. Read
this article in the NY Times on what it is like to be a ghost writer. Note that it is surprisingly common that chefs do not read their work before the book goes out to print.
OK, rant over.
When I first started cooking, I bought the same typical cookbooks that most people would buy and followed their recipes exactly. Over time I started to see that most of these books were full of mistakes, and their mistakes become yours. Even classic cookbooks like
Larousse Gastronomique and Escoffier are products of their time - modern cooking methods and modern taste have rendered many of the recipes obsolete. For example, very few people make a demi-glace using brown roux anymore. The reason is that brown roux produces a heavy, floury texture and the starch itself locks away flavour molecules. A modern demi-glace is simply a reduction, calling for more gelatinous cuts and relying on the gelatin to provide thickening. It is lighter and more flavoursome, because there is less water, less foreign ingredients, and more beef.
Over time I became frustrated with these books and yearned for more understanding. The lightbulb moment came a few years ago when I watched Heston Blumenthal's
In Search of Perfection series on TV. In each episode, Heston would pick a dish (say, a hamburger) then visit a whole bunch of restaurants that made excellent hamburgers. He would test the beef and conduct experiments on how the burger should be designed and what flavours should be in it. At the end of the episode, he presents a recipe that he and his chefs have developed as the "best possible" hamburger. The main insight I gained from this series is that
cooking technique counts. To me, this was a new way to look at food and set me down a new path.
All the books show in the images above should be in your purchase list. These are excellent recipes developed by top chefs which can be made in home kitchens. Even if some of the recipes from "In Search of Perfection" are too complicated, you can still make individual components of it.
The next most influential book I bought was Harold McGee's book
On Food and Cooking. Heston frequently refers to this book as his kitchen bible. It definitely is that. This book contains no recipes. Rather, it has a series of chapters devoted to subjects such as poultry, meats, eggs, dairy, pastry, vegetables, etc. In each chapter he describes the science behind the subject. Reading this book gave me plenty of new insights. One example - An angel food cake batter is essentially a batter leavened with an egg white foam. The idea is to set the foam before it has a chance to collapse. Oils cause foams to collapse because it interferes with the surface tension of the foam - so do not introduce oils to the egg white foam until the very last minute. This also explains why the presence of fatty egg yolk - even the most miniscule droplet - interferes with the formation of an egg white foam.
Other good "science-y" books include
What Einstein told his Cook and its sequel,
Cooking For Geeks, and
Culinary Reactions.
By now I was thoroughly into the Modernist movement with its emphasis on science and new techniques. Probably the crown in the jewel for the Modernist movement is
Modernist Cuisine and its sequel,
Modernist Cuisine at Home. The problem with
MC is that it specifies too many specialized equipment (CVAP ovens, centrifuge, etc) and specialist ingredients (N-Zorbit M, Carageenans, Xanthan gum, transglutaminase, liquid nitrogen) but many of the recipes can be adapted for the home. The other problem is its hefty price. In fact this book gives you a tremendous insight into cooking.
MC@H is much more approachable.