the vegetarian meals I love the most that fit in your guidelines are:
Vegetarian chili - I add lots of vegetables and different kinds of beans everytime but I absolutely LOVE homemade chili. It's pretty fast and can make a lot or a little. I like to make a lot and save the rest for lunches and dinners.
Veggie lasagna - this has to be a favorite of mine because you can change the type of vegetable used and completely change the flavor - eggplant, zucchini, spinach, mushrooms.. all do well. The great thing about this is that you can cook once for more than one meal and lasagnas are fairly sturdy as far as the freezer goes. Just cut out single serving portions and you have some quick meals for later.
If you like tofu there is a lot you can do with that because it basically takes on the flavor of whatever its cooked with. stirfrys are so easy and quick to cook. Also very versatile - you can throw just about any vegetable together with some garlic or your favorite spices.
Ethnic foods in general have lots of vegetable options. I like fried rice or lo mein with lots of vegetables, stirfrys like I said before... Enchiladas, burritos, tostadas, tacos - all can be made vegetarian. Pizza is a great FAST one too! You can use cheese or no cheese its great either way. If you use an english muffin half, a dab of tomato sauce and your favorite vegetables you can have a delicious lunch in 5 minutes.