This is my first year in over a decade, and my first year as a vegetarian. I'm curious as to what local restaurants/food resources other non-meat-eaters have availed themselves of? 

Old Spaghetti Factory generally has good options.  Their broccoli side is delicious.

I also like Panera Bread for breakfast options, especially.

There used to be a Noodles and Co., but they flooded and closed a few years back.

I haven't tried it, but a lot of people recommend a place called Purple Carrot.

Believe it or not, Yard House has a lot of meat replacement  Gardein, if that's something you like.

Bear in mind I haven't been to Indy since 2019, so there are probably more places I don't know about.

Old Spaghetti Factory is right next to the local escape room which offers tickets in the events.  Last year it made for an easy lunch place after the game.

I tried to pay attention whenever I heard a recommendation for a great vegetarian place since one of the guys I usually go with is a vegetarian, and I have heard several good things about Public Greens (https://www.publicgreensurbankitchen.com/) and Tinker Street (https://tinkerstreetrestaurant.com/indianapolis-tinker-street-food-menu) though neither are right by the convention center certainly

These are very helpful! I can (and do) Google stuff, but it's helpful to hear more anecdotal reports about what folks like.

I always enjoyed Three Carrots (https://www.threecarrotsfountainsquare.com/), which is vegan. While they no longer have the downtown location, Fountain Square isn't very far away (and is a nice place to visit in the city).

Forgot to mention, many of the food trucks will have vegetarian or vegan options.  If you have some time, check them out.

Go to Google Maps. 

Zone in over the ICC and Lucas with about 3-4 city blocks around.

Type in "vegan food" into the search box. 

You will find about half a dozen Vegan restraunts and shops offering Vegan meals, including a Vegan vending machine at Floor 1 · Hyatt Regency Indianapolis.