Add quinoa and vegetable broth to a medium saucepan over medium high heat. Bring to a boil.
Once boiling, turn the temperature to low and cover with a lid. Let the quinoa simmer for 15-20 minutes, until the quinoa has soaked up all the broth.
Remove the quinoa from the heat and fluff with a fork. Let cool completely.
Add the cooked quinoa to a large bowl with the black beans, corn, bell pepper, tomatoes, red onion and cilantro. Set aside.
In a small bowl, whisk together lime juice, olive oil, salt and black pepper.
Pour the lime dressing over the quinoa and toss until coated. Let refrigerator for at least an hour or ready to serve.
Before serving, toss with diced avocado.