Cover a large plate with paper towels. Slice the tofu into 4 pieces. Place the pieces of tofu on top of the paper towels, cover the tofu with additional towels, place another plate on top, and place some cans on top of the plate as a weight. Set aside and allow the tofu to press for 30 minutes. Meanwhile, in a non-stick skillet, saute the onion, shallot, and celery in olive oil for 5 minutes. Add the portabello mushrooms, garlic, basil, and oregano, and saute an additional 5 minutes. Cook the vegetable mixture until all of the vegetables are tender and all of the mushrooms juices have evaporated. Set aside to cool. Using your fingers, crumble the pressed tofu into a large bowl. Add the sauteed vegetable mixture to the tofu and gently fold together. Add the breadcrumbs, pecans, vinegar, tamari, and pepper, and stir mixture until well combined. Using a 1/2 cup measuring cup, portion the mixture into 6 patties. Slightly flatten them with your hands. Cover the patties with plastic wrap and allow to chill for 1 hour. In a non-stick skillet, using a little canola oil, cook the patties, in batches, until browned on both sides. Serve the burgers on buns with your favorite toppings and condiments.