Preheat your oven to 350°F / 175°C.
In a 2-quart casserole dish, combine the lentil soup, rinsed black beans, sliced mushrooms, carrots, corn, water, uncooked barley, uncooked bulgur, chopped onion, black pepper, and salt.
Stir everything together until well combined. 2.
Cover the casserole dish and bake for 1 hour and 15 minutes, or until the barley and bulgur are tender. Be sure to stir the mixture twice during the baking time to prevent sticking and ensure the grains cook evenly. 3. Carefully remove the casserole from the oven, give it one final stir, and sprinkle the shredded cheddar cheese evenly over the top. 4.
Cover the dish again and let it stand for 5 minutes. This allows the cheese to become perfectly melted and gooey before serving.
Sauté the onions and mushrooms in a little olive oil before adding them to the casserole. This simple step deepens their flavor and adds a wonderful aromatic base to the dish.
Don't be afraid to add more spices! A teaspoon of smoked paprika, cumin, or a pinch of red pepper flakes can add a lovely warmth and complexity to the casserole.