I like pasta + canned meat + instant gravy + vegetables. You use the water left over from the pasta to make the gravy, and the formula gives you a lot of variety if you vary the kind of meat (tuna, sardines, chicken, etc.), gravy (country, chicken, brown, etc.), and vegetables. Sardines and country gravy is surprisingly good. Avoid vienna sausages, they're possibly the worst thing I've ever eaten that wasn't a dare.
As for vegetables, get what you can locally. Broccoli, snow peas, and green beans travel well, so you can use the leftovers the next day or two if you have more than you want to eat in one meal. Broccoli and snow peas are also good to snack on during the day. Asparagus can be really good, but travels poorly and becomes slimy if left in your pannier on a hot day.