If you are looking for an above average veg restaurant in Vashi, I'd suggest Cafe Vihar located at Regenza Tunga.
Good location, closer to station, bang opposite inorbit mall. Simple yet nice ambiance. Good number of tables spaced out. Tends to get a bit noisy on weekends.
The staff is prompt and polite. They have a good knowledge of the menu and also come up with suggestions as per the guests choice.
They serve South Indian, chaats, North Indian and Chinese.
I was here for dinner one weekend and called for Paneer Chilli in starters which I loved. It wasn't too spicy. Also ordered for a Masala Papad which was alright. Paneer Lasooni along with naans are the best bet. Avoid garlic naan with this dish since you may end up getting an overdose of garlic. Lastly we called for Hyderabadi Biryani with which I again didn't have complains. It was nicely cooked and didn't have too much of spices and condiments that I've experienced at other places.
Overall I loved the food. The place is fairly priced. A good meal for 2 would not cost you more than Rs 500. Its definitely going to be one of my regular joints for veg food when I'm in Vashi.