It's actually really easy to make a vegan pizza. I'm not even a vegan and I do so fairly frequently. All you need is any dough recipe that doesn't use eggs. For toppings, just load that bastard down with fresh veggies, such as onions, peppers, tomato slices, whatever sounds good. For a big punch of flavor, apply garlic and onion liberally.
Now, here's the odd part... You're not using cheese, which normally holds everything together on a pizza. So for this method, we are going to use the sauce. We're going to start out with a thick, chunky tomato sauce, seasoned with oregano, onion, garlic, thyme, and cumin. Heat it up in a pan and let it simmer, meanwhile you're going to stir a spoonful of corn starch into a bit of hot water. Mix this into your sauce and let it simmer long enough to thicken up... the starch will make it thicker and 'gloppier' than the sauce already was.
Pre-bake your crust for a few minutes, then put all the toppings on *before* the sauce. Cover the whole thing in sauce, leaving some space at the edges for things to flow outward. With a grill brush, paint some olive oil onto the still-exposed edge, and sprinkle the whole thing with black pepper.
Bake at 400f for 15-20 minutes, or until the crust is browned and the sauce is bubbling.
Take it out, let it cool, and enjoy. It's slightly messier than a pizza with cheese, but not terribly so, and it's packed with flavor.