Preheat your oven to 375ºF. Spray a large casserole dish with non-stick cooking spray to prevent sticking and make cleanup easier.

Add the diced onion, peeled and cubed sweet potatoes, taco seasoning, vegetable broth, salsa, rinsed quinoa, green chilis, drained and rinsed black beans, and diced tomatoes into the prepared casserole dish. Mix everything together well to ensure the seasoning and liquids are evenly distributed.

Cover the casserole dish tightly with tin foil. Bake in the preheated oven for 30 minutes, then remove the dish from the oven and stir well to help the quinoa cook evenly and keep the flavors balanced. Recover the dish with tin foil and return it to the oven for another 40 minutes. I like to check for doneness by making sure the sweet potatoes are fork-tender and the quinoa is fluffy.

Take the casserole out of the oven and let it sit, covered, for 10 minutes before serving. This allows the flavors to meld and the casserole to set a little, making it easier to serve.

Serve the casserole hot, garnished with fresh cilantro, sliced avocado, and a squeeze of lime juice for a bright and fresh finish. For a burst of flavor, I always like to add a generous squeeze of lime over the top right before serving.