Finding good choices for lunch when you are traveling is always hard. On Sunday during our long trip home we stopped at Mojave Thai Cuisine. It is an unlikely restaurant in a desert town. We had our favorite Thai dish, spicy Thai basil with eggplant and tofu. Since I do not know all the ingredients, I cannot say for sure whether it is vegan or not but it is vegetarian and delicious! We stopped here once before on our travels and we asked for it spicy and it nearly blew our heads off. This time we asked for medium spicy and it was toned down just enough.
Look into ethnic restaurants on your road trips. Often their food is fresher and healthier than fast food burgers. Plus you will probably have some leftovers to take home with you for dinner!