The relatively new ZEN VEGETARIAN RESTAURANT on Flatbush Ave is AMAZING. It's on par with Red Bamboo with a menu full of delicious alternatives to eating animals or animal by-products. It's a little pricey, but definitely average for this kind of food. Their delivery is super fast and friendly, too. I highly recommend them.
I am always searching for great recommendations around Brooklyn, but this is one of my first times offering a recommendation, myself!
773 Flatbush Avenue between Clarkson Avenue and Lenox Road; it has a black awning, so it's easy to miss.