Fresh vegetables (like radishes, jicama or mini cucumbers) with or without dairy and herbs. Fruit or vegetable or mushroom chips if fresh ones are not crunchy or dry enough for your palate. I am not sure why you are supposed to only eat fruit and vegetables? You can have eggs & meats ans soups for breakfast. Hot broth is actually far nicer than coffee as a morning picker-upper. You probably would get replies about various nut-based granolas and the like, but I would advise against it.