First, YOU don't approach the publisher, your literary agent does.
The first thing you need to do is get a literary agent interested in the concept for your book. You do this by sending a query packet to a bunch of lit agents that focus on food related publication. A query packet contains a cover letter,a query letter, the introduction to your book, and outline and a completed chapter or two. The query letter introduces you, your background and experience, describes your book in a paragraph or two, and a paragraph about why readers would want to purchase and read your book.
Send these packets to every literary agent you can identify. Then, once you get one to bite on your project, your agent will shop the concept to a bunch of publishers. He or She may or may not be able to get a publisher to sign on to the project. If you do, then your agent will negotiate all the details, including what you will get paid, how much advance you will receive, who your editor will be and how much you will get paid for each copy once the book is published.
There is a very good book that provides information and advice for food writers of all kinds. It's titled Will Write for Food by Dianne Jacob. She explains how to go about getting all types of food writing work.
Keep in mind that few food writers actually make any money when publishing a cookbook or expose. These books are usually best used as promotional materials for chefs and food writers to help launch careers in consulting, TV personality stints, editorial contributions etc.
Good luck to you. | 
