Full confession: I read cookbooks like novels.
The best cookbooks, in my opinion, are those with great descriptions of the recipe that turn it into a story. History of the recipe or the ingredients. This can be family history or history of a country or ethnic group. Where does the recipe come from? How does it fit into food culture?
If done well, you can also incorporate stories that aren't as cook-booky. You can even write cookbooks that are novels.
While I wouldn't buy this book for the recipes alone, it has plenty to share. One of my favorite books of all time... Like Water for Chocolate. The recipes have their own following too. Aztec Chile Truffles, Spicy Grilled Chicken with Creamy Pumpkin Mole Sauce, Polpette di Fagioli...how can you go wrong?
Back on the nonfiction side, Joan Nathan is famous for her cookbooks with commentary included. For example:
The Jewish Holiday Baker Drawing upon the recipes,
stories, and secrets of a baker’s dozen of bakers from around the
world, she captures the art of Jewish baking....The bakers who have perfected these recipes represent the breadth of
Jewish history and geography: they come from America, Israel, France,
Italy, Spain, Mexico, Hungary, Germany, Poland, Czechoslovakia,
Russia, Syria, and Egypt. Their personal stories offer a fascinating
window into the Jewish experience of this century.
I would be remiss if I did not mention my very favorite food historian / cookbook writer / everything to do with food, Michael W. Twitty, author of The Cooking Gene. If you haven't read his book and blog, it will change forever how you view food writing.
Cookbooks as history, travelogue, memoir, ethnology, and so much more. That's part of what you can aim for.
Normally the commentary is in the header on the specific recipe page. Other times there is an introduction to a section of recipes. This works especially well if your cookbook is organized geographically or historically. You can also write in the introduction to the book, or in chapters before the recipes. Or you can do it however you want.
Food writing is a genre that is growing and spinning and creating. There is more creative energy in food writing now than ever before. Whether you just include a few notes about the technical aspects of the recipe, or you infuse your family's life history into your pages, a well-written cookbook will do well.