Vegetarians and vegans: What is your ultimate veggie or vegan burger like?

I am a vegetarian who loves burgers. It’s not so much the actual burger itself although a good veggie patty can make or break my day, but that’s just because I love food as it is what’s on the burger. A Red Robin recently opened up near my mom’s house and they have the option to switch out any of their beef patties for a veggie or vegan patty at no extra charge. Because of this, I have been reveling in all of the different Red Robin burgers. Now, of course, I want to start preparing my own at home. For me, my favorite burger toppings are guacamole, some kind of cheese, mushrooms and tomatoes.

What about you, collective, what do you like on your veggie burgers?