I have a great deal of admiration for people who cook every day on the trail. When I'm at home, I cook up a storm--weekends, evenings, sometimes I get up early on work days just so I can make something decadent like blue corn waffles with blueberry-ginger-maple sauce. But out on the trail I become a completely different person. A minimalist, a functionalist. I leave my domestic instincts behind--or perhaps they shut themselves off after a few days in the woods. When I hike, I am a no-cook fiend; I don't bring a stove unless the temperatures will likely be sub-freezing; then it becomes worth it to have hot tea in the morning and hot soup (try instant miso--it's addictively salty) in the evening.
My primary concerns are ease of preparation and nutrition. For instance, I am a big fan of sprouted quinoa while hiking. Bring an airtight container, one you trust not to open and spill, and fill it with quinoa and clean water. Change out the water at least once a day, preferably twice, and after one or two overnight soaks the quinoa seeds will have cute little tails. Soaked quinoa has a higher vitamin content than cooked and is more easily digestible. Throw in dried herbs/spices of your choice, perhaps some Herbamare or lemon salt. Also very nice topped with toasted salted sunflower seeds, or curried cashew pieces, with some freeze dried veggies such as peas and corn tossed in... sprouted quinoa is an endlessly variable no-cook base. And remember, it is not a grain but a seed; if you feel over-carbed and under-proteined, this might be your best friend. Try quick-cooking quinoa flakes for breakfast in place of oatmeal.
Although I've been veggie for some years, I went through a fish phase several years ago when I was worried about my BMI being too low. Those tuna packets are great, and you can mix it up by bringing some salmon ones too. They contain everybody's favorite omega-3s, to keep skin, joints, brain, etc all functioning properly. My favorite method of preparation is a packet of olive oil plus some lemon salt, then roll it all up in a tortilla. I cannot overemphasize how nice lemon salt is on the trail. It has the magical power of making almost anything taste fresher.
Also--don't hesitate to bring hard cheeses. Parmesan and asiago, as well as alpine styles like gruyere, and that old standby aged cheddar, are great traveling foods, and a little goes a long way toward making plain pasta or crackers or what-have-you taste more like "real food". General rule of thumb: the harder the cheese, the longer it will keep.
Also, I always allow myself some fresh food treats that I know will pack well: apples, carrots, radishes, green beans, and snap/snow peas are all good options. If I'm out for an extended trip, I make sure that whenever I hit up a grocery store I grab something extra-special, like a ripe avocado (awesome mashed up with lemon salt--LEMON SALT!--and slathered on a bagel or tortilla) or a couple of pieces of fruit, and eat them within the next day to keep weight down and keep them from getting too bruised. I know my own body, and I know that the vites and minerals in fresh whole foods leave me feeling more energized than any protein supplement can. I always pack sea vegetables, like nori sheets, or dulse, for the same reason. Tons of minerals and a great easy salt-fix.
I concur with those who vote for more snacks. I rarely break out dishes and silverware for midday eats; I prefer having things to nosh on the go, and on a nice day I'll make several short stops to appreciate good views and snack on things like tamari almonds (can't leave home without em), sesame cracker sticks (ditto), dried fruits (especially figs and apricots), chocolate chips, and the occasional energy bar.
That's a pretty thorough rundown of my trail staples. Oh! One final word: bring tea bags for flavored water! I love green or oolong tea steeped for an hour or two in cold water; the flavor is smooth and refreshing and it's a good mellow caffeine boost.
Very few of these are things I prepare for myself on a regular basis at home, but they do the trick when you're out in the woods. Everything tastes better on the trail; I've never had a lot of luck testing out trail recipes at home because I am just never starving enough for the prospect of something like freeze-dried veggies or vacuum-packed tuna to be appetizing. The best way to find out what you like is to get out and do some field tests!