For the salad, combine vegetable broth and quinoa in a medium saucepan and bring to a boil. Reduce heat, cover and simmer until the germ of the quinoa is exposed and all of the liquid is absorbed, for 15-20 minutes. Remove from heat.
While the quinoa is cooking, combine the remaining salad ingredients in a large bowl.
For the dressing, combine all of the ingredients (EXCEPT the olive oil) in a food processor. Pulse to combine, scraping sides of bowl to blend all ingredients. Turn on the processor and then slowly stream the olive oil through the top opening, continuing to process until the dressing is combined.
Combine black bean/corn mixture and quinoa. Pour the dressing over the mixture. Serve chilled or warm. Top with additional cilantro if desired.