Begin by writing down your random thoughts about food. It is such an important part of our lives that you should have no problem filling a page, three or more just be brain-storming ideas.
Welcome your new blank book and in it, keep all kind of food-related information. When writing seems inadequate, add your own sketches. When pen and pencil don't satisfy, add color. Buy sets of markers, watercolor pens, crayons, a watercolor box of basic colors, and let your ideas bubble over onto the pages.