Heat the oil in a large heavy soup pot over medium low heat. Add onions, and cook until soft and they start to turn brown (about 10 minutes). Add the garlic, and cook for about 2 minutes.
Add the tomato paste, chili powder, cumin, and oregano and cook for about 2 minutes, stirring constantly. Add the beans, stock, and potatoes, and season with salt and pepper. Cook for about 5 minutes, then add the quinoa.
Continue cooking for about 15 minutes - 30 minutes, stirring frequently, until quinoa and potatoes are cooked and the chili has thickened. Add a bit of water if the chili becomes too thick for your liking. Top with avocado and chopped cilantro. Scrumptious!
makes 6 hearty bowls of chili