Heat the olive oil in a large skillet over medium-low heat.
Add the diced onion and sauté until tender, about 4 minutes.
Add the minced garlic and cook for 1 minute more, stirring so it doesn't brown.
Stir in the rinsed quinoa, drained black beans, chili powder, cumin, crushed red pepper flakes, black pepper, canned green chiles, canned diced tomatoes, and vegetable broth.
Bring the mixture to a boil, then reduce heat to a low simmer and cover.
Cook for 15–20 minutes, or until the liquid is absorbed and the quinoa is tender.
Remove from heat, keep covered, and let sit 5 minutes.
Fluff the quinoa with a fork or large spoon, stir in the chopped cilantro, adjust salt to taste, and serve.
