After 15 years in SE Asia and 10 years partnered with a Pakistani - I know Indian/Desi food. When I returned from abroad to the DFW area I checked out several Indian restaurants. When I at last found Gopal Vegetarian Restaurant I felt like I was home (in Asia)...this is as authentic as it gets. The food is south Indian and 100% vegetarian (some dishes are vegan). Non-Indians are rarely found here and it can be a bit difficult to figure out the procedure - the various employees speak varying degrees of English.
There is a limited menu, but the best option is to order a "thali" (large plate/many choices if you are very hungry), or a "shaak" (smaller, less options). The thali/shaak plates come with whatever options have been prepared for that day - you are not able to chose. You can, however, choose the bread to go with your meal: "puri" (a fried bread similar to a sopapilla), "roti" (flat bread similar to a tortilla); "chapati" (thicker kind of flat bread).
The drink option is very limited as well. They have Indian style hot tea (chai), bottled water & sodas (not regularly stocked tho). I've taken to bringing my own bottle of water, in case they have nothing.
The price is inexpensive, especially for the quality/quantity of food. The ambience is non-existent, but authentic - this is exactly how inexpensive eateries are in Asia. The place is very small (7 tables) and can fill up quickly during busy times. Unfortunately it can be loud and distracting when people bring their children and let them run around the restaurant (pretty common in Indian culture).Pros: authentic S. Indian, delicious, inexpensive
Cons: no atmosphere, can be noisy, can be intimidating for unexperienced