Preheat oven to 375. Cook the quinoa according to package instructions. While the quinoa is cooking, slice the tops off the tomatoes and hollow out the insides. Set aside.
Stir the beans, corn, cilantro, nutritional yeast, ancho chili powder, salt and pepper into the cooked quinoa. Evenly divide the filling among the tomatoes and bake for 20 minutes. You may end up with extra filling depending on how large your tomatoes are, but that's alright because it's also delicious on its own.
Serve with sliced avocado, cilantro and a generous squeeze of lime.