As I see it, there are two different kinds of eating on tour. The first is the food you buy and eat right away, say sandwiches during the day. The second is the food that you carry for cooking at a later time, say at a campsite.
I try to stock up on daily foods, like sandwiches and other "eat directly" stuff, before I leave for my day's ride. I look for sandwich shops, grocery stores, or restaurants where I can get a "to-go" meal, fruit, or something else I eat while on the road without cooking.
I also try to carry cooking ingredients for two meals (usually dinner that night and breakfast the next morning). I always try to get some fresh vegetables (broccoli is my favorite) to add to pasta or oriental noodles. I usually have oatmeal for breakfast, if there isn't a restaurant near where I have stopped.
As for ingredients, I carry pasta or raman, oatmeal, olive oil, soy sauce, corn starch (for making a sauce), crushed red peppers (packets from a pizza place), Parmesan cheese (again from a pizza place), sugar packets from a restaurant, cinnamon, salt and pepper. In a pinch, pasta, olive oil, parmesan cheese, and crushed red peppers will make a palatable meal.
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