Heavily Inspired by Hawkeye .
Hawkeye in the above mentioned post did a literal favorite list for almost every tambrahm. Since most of the items I wanted to cover was already done, I thought of listing all the veggie food that you get in US restaurants.
Chipotle: The Burrito Bowl with the Fajita veggies option - Can be had in the normal burrito version but ends up difficult to manage to eat and gets messy. But taste and cost-effective. The combo should typically be Rice, Black beans, grilled veggies, mild salsa, sour cream, corn, cheese, guacamole and lettuce. You can add another type of salsa depending on your hot and spice preferences. This is almost too heavy for anybody to have it at one go - so its always a better idea to have it made as a to-go option. The taste is simply unexplainable in words.
Tijuana Flats - The Black Bean Flautas with all veggies and queso and sour cream-guacamole sides. Make this on a wheat shell, if you really care about the calories. The other dish that would appeal to the sapaaturaaman/raami in you would be the Spinach and Artichoke or Black Bean-Veggie Quesadilla. The best thing about TF is the Smack My Ass and Call Me Sally Sauce Bar - There are four levels - Sissy Sauce, Middle Weight, Tear Jerker and the Death Wish. Even though I have high tolerance to kaaram/hot-spice levels, personally their death wish is quite harsh on your taste buds. But quite a few in the middle weight and tear jerker might make you remember your avakkaai urugaai days back home.
P.F. Chang's Bistro: Quite a pricey option but quite tasty. Amongst asian cuisine restaurants, I find that these guys have the best appetizer - CHANG’S VEGETARIAN LETTUCE WRAPS. It comes with a few leaves of Lettuce and fried shredded tofu and some other stuff which I think is vegetarian (as the menu promises us) and I can tell you that you will most probably ask for a appetizer refill. The Stir Fried Eggplant and Buddha's Feast are the entrées that will make you feel like a well fed python.
Olive Garden - The Eggplant Parmesan and the Five Cheese Ziti are almost the de facto choice of veggie junta. Between these two I always end up buying the Eggplant dish, throw away the Spaghetti and substitute from the 5 Cheese Ziti (which by itself is too heavy for me). But this mandates that: 1. You either go with someone with whom you are comfortable to share food dishes (echchai and all that aacharamaana stuff) or be filthy rich enough to get 2 dishes and waste some portion of it.And having spoken about OG, it would be unfair to miss the salad bowl that you get. In fact, if only OG cuts out oh-we-are-a-classy-restaurant-and-so-you've-got-to-wait-15 mins-to-get-seated attitude, I think the best lunch deal in US is the Salad-Soup combo available here.
CheeseCake Factory: Again, a pricey option, but its a veggie lovers heaven in terms of variety. Almost every pasta can be ordered without meat and more often than not, the waiter suggests an alternate vegetable that almost always is spot on. And the less said about the deserts, the better (I mean this as a compliment). Anybody who is trying to lose weight stay away from this place. The cheesecakes are so rich and tasty that you won't notice that they almost choke you with their creaminess and cloyingly sweet taste.
Maggiano's Little Italy: The USP of this place is that they make the dishes from the scratch for your order. So as long as you have a knack of substituting the correct vegetable for meat, you will end up with quite a good dish. But the Eggplant Parmesan with the provolone cheese makes the eggplant parmesan at IG pale in comparison. But on the flip side, this restaurant has a 'iruttu' decor which sometimes will jar you if you are a person who prefers bright settings. And the Tiramisu - the best tiramisu you can have outside of Italy, is perhaps here. You don't get a nasty whiff of rum at the end and the texture is just divine.
Taco Bell: Cheesy Fiesta Potatoes, Crunchwrap Supreme, 7-Layer Burrito and bean Baja Chalupa. This is something I picked up when I was a student and I still give in to the temptation once in a while. Obviously not healthy to you (might be for your wallet). But it is like the road side pani puri that you get back in India - the taste overwhelms logical (hygenic) reasons.
ColdStone Creamery: If you love ice-creams, you should have been to this place at least once. Amazing texture and God Save You if you have the 'Gotta Have It' size. You can feel the fat calories adding up around your waistline before you find the last scoop of the custom made ice creams. Their ice creams are really sinfully delightful.
German Cuisine - I do not know of any national chain German restaurant - but I don't think you get the cream of potato soup, called Kartoffelsuppe any richer than in a German restaurant. And depending on how good an eater you are, you might want to try the Spaetzle (noodle-like dish) and the potato pancakes. I personally would not recommend the Sauerkraut - but have seen some veggies love that too.
Chili's: The sizzling fajitas - substitute chicken with veggies - but warn the waiter makkal not to include too many veggies. For those not really intent on doing work, you can have quesadilla version. The Texas Cheese fries are amazing, possibly, the best fries in the US. And the molten chocolate cake (Dark or White) is again, up there amongst the best deserts in the land.
I think I have covered most of my favorites. Have left obviously on your face options such as Subway, Greek cuisine etc as they are common and don't score really high on the taste charts. (This comes from someone who eats a subway sandwich almost once in 5-6 days)