Preheat the oven to 350°F (175°C). Grease a 9-inch (23 cm) baking dish with olive oil.
In a large bowl, combine the cooked lentils, cooked quinoa, onion, carrots, celery, mushrooms, breadcrumbs, nutritional yeast, olive oil, garlic powder, oregano, thyme, sea salt, and black pepper. Mix until all the ingredients are combined.
Transfer the mixture to the prepared baking dish. Press down with the back of a spoon to form an even layer.
In a small bowl, mix together the tomato sauce and balsamic vinegar. Pour the sauce over the lentil mixture and spread evenly.
Bake for 30 minutes, or until the top is golden brown.
Let cool for 10 minutes before serving.
Interesting Facts
Lentils are an excellent source of plant-based protein.
Quinoa is a great source of vitamins, minerals, and fiber.
Tomato sauce and balsamic vinegar add a hint of sweetness and tangy flavor to the lentil loaf.