Heat olive oil in a large non-stick saucepan over medium-high heat. Once hot, add onion and sauté until golden and tender. Add in garlic and sauté 30 seconds longer. Stir in broth, diced tomatoes and green chilies, cooked quinoa, chili powder, cumin, paprika, cayenne, and season with salt and pepper to taste. Bring mixture to a boil, then reduce heat, cover saucepan with lid, and simmer about 20 minutes, until mixture has thickened.