Rinse the quinoa under cold water thoroughly. In a medium saucepan, bring the vegetable broth to a boil. Add the quinoa and reduce the heat to low. Cover and let it simmer for about 15 minutes, or until all liquid is absorbed. Remove from heat, fluff with a fork, and set aside.
While the quinoa is cooking, heat the olive oil in a large skillet over medium heat. Add the diced onion and sauté for 3-4 minutes until translucent.
Add the minced garlic and diced bell pepper to the skillet and cook for another 3-4 minutes until the bell pepper is soft.
Stir in the black beans, corn, diced tomatoes (with juices), cumin, and chili powder. Season with salt and pepper to taste. Cook for about 5-7 minutes, stirring occasionally, until everything is heated through.
Add the cooked quinoa to the skillet and mix well to combine all the ingredients. Let it cook for an additional 2-3 minutes, allowing the flavors to meld.
Serve the quinoa mixture hot, topped with diced avocado and fresh cilantro. Provide lime wedges on the side for an extra zesty flavor.