A vegan kitchen contains vastly different things than a regular one.  I made the conversion on a barebones budget, so I know the recipes can seem overwhelming at first.  Just pick up a new ingredient or two as you can afford them, and soon you'll be all set.  In addition to what VeganHippie mentioned, try other soups (cheap), Mexican (burritos, tacos, enchiladas), stir fries, other pasta sauces, curries.  I tried to try something completely new at least once a week.  I guess the best advice is to be bold and try things you aren't quite familiar with.  

chana masala, curry of furry in a hurry, chick peas and spinach in tahini sauce, homemade veggie or bean burgers, spaghetti, bean enchiladas, pizza

youre offering to cook meals for her but she only wants microwaved food?  whats wrong with this person?

i have an idea, you can come cook for me and then take a tupperware container of leftovers home for her to microwave!  everybody wins!

yeah really, why does she care how you cook it, as long as you are doing it, she should be happy!!!

Does your gf know how to cook at all?  It seems a little weird that she's expecting you to bend over backwards for her eating habits...  Unless of course you are vegan as well.  But I know it was really fun for me to learn how to cook once I went veg, so maybe the two of you could do some cooking together?  It can make a longer prep time seem shorter if you're having fun doing it.

But, a simple suggestion (if you like asian food):
chop up some onions and peppers (red bell works best) and throw those in a frying pan or wok with some oil (sesame is best).  Fry for about five minutes.  At this point add some pea pods, mushrooms, broccoli, baby corn, water chestnuts, or any other veggies you like in a stir fry.  Also add some tofu or seitan or fake chicken/steak strips.  Fry for a few more minutes, or until everything is cooked but still slightly crunchy (if using frozen fake meat, you should prolly throw that in with the onions and such so it thaws all the way).  Now add your sauce.  I usually do a mix of a dark stir fry sauce, sweet chili sauce, sweet and sour sauce, and chili flakes.  It's spicy but flavorful, and a little different every time.  But you can buy tons of bottled sauces, so play around with what you like.  Serve with white or brown rice.  The whole thing (prep included) takes about thirty minutes, if that (I start my rice in my cooker and am done with the stir fry by the time the rice is done), which I suppose is longer than 15 minutes but not by too much (it's quicker if you are fast at cutting veggies, which I am not, and if you use instant rice and multitask by cutting the second round of veggies while the first cook and such).