Traditionally (at least during our lifetimes) dinner revolved around a meat dish, with a starch and some vegetables on the side. So, when we change our eating habits and cut out the center piece of the plate what’s left?
I think the easiest approach is to begin with meals like soup that basically stay the same, the contents of the soup change, but you still serve it with something like bread and salad. The soup could either be traditionally vegetarian, like Minestrone, or you can substitute beans for the meat in a family favorite. Often the meals are similar to those in a more “traditional” diet plan they’ve just been altered to remove the animal products from the meal. For instance spaghetti without meat, possibly with extra vegetables added to the sauce. Lasagna, again without the meat, and with a tofu based ricotta substitute and optional vegan cheese. Burritos can be made with just beans, rice, salsa, and veggies. Substantial sandwiches can exist without the addition of lunchmeat and cheese. A salad can fill the role of main course also, just include ingredients that are filling like beans or tofu along with the vegetables.
For those whose feet are firmly planted in a vegetarian diet, tofu or tempeh dishes can become the center of a meal. Another option is a composite type of dinner, made up of many smaller dishes. This could include several vegetable side dishes and then a grain or bean dish to go along with them. I like to combine all this into a one dish meal using a grain and bean salad with a variety of vegetables thrown in.
As far as what vegetables and side dishes should be combined with which main course – I say, look at the colors. If dinner is split pea soup (yum), a bright yellow veggie would be a great addition. If you’re using a lot of greens, cooked or raw, red peppers, tomatoes, and grated carrots are all excellent additions. On the other hand, if you are eating carrot bisque, some sides like edamame, steamed broccoli, or even green beans would work well. You get the idea.