In a medium saucepan, add the quinoa, vegetable broth, olive oil, salt and 1 cup of water. Stir to combine. Bring to a boil over medium-high heat, then reduce to a simmer. Cover and cook for 12 to 15 minutes until the liquid is completely absorbed. Fluff with a fork and allow to cool for 10 minutes.
While the quinoa cools, prepare the salad dressing. In a medium mixing bowl, whisk together all of the ingredients until emulsified.
Put the cooled quinoa into a large serving bowl. Add the black beans, corn, tomatoes, green onions and salad dressing. Toss to combine. Season with salt to taste. Garnish with cilantro leaves and Cotija.