Quinoa: Add the quinoa, water and onion, plus a pinch of salt to a large pot, over high heat. Bring to a bowl. Then close wit lid and reduce heat to low. Simmer for 17 minutes, then turn off the heat, but do not remove the lid yet. Let quinoa sit for another ten minutes with the lid on. then uncover and fluff the quinoa with a fork.
In a small bowl, whisk together the dressing. Set aside.
In a large mixing bowl, combine the olives, spinach, black beans, bell pepper, corn and the dressing. Toss well.
Fold the quinoa into the large bowl of veggies. Allow the warm quinoa to wilt the spinach and help marinate all the ingredients together.
Do a taste test! If you want more flavor and spice, you can make another batch of the dressing and fold it in, or add to taste as you serve. Another way to add flavor is to add some nutritional yeast or plenty of hot sauce or salsa. If you like more salt accents, add salt and/or black pepper to taste.
If you want a warm and more casserole-like presentation, you can pour the mixture into a large baking dish, cover with foil and bake at 350 degrees for ten minutes to marinate all the flavors together and soften the veggies further. Otherwise you can serve as is, or even quickly warm further on the stovetop or even in the microwave.
Scoop the mixture into serving bowls over top a bed of leafy greens - kale or spinach works well. Add the chopped avocado over top. Add hot sauce or salsa to taste. You can serve this as a bowl, or add some corn tortillas for fiesta tacos. Crushing corn chips on top of your bowl is also a nice flavor-boosting option.