While sweet potato is roasting, heat olive or avocado oil in a large non-stick skillet over medium high heat. Once hot, add onion and saute until the onion begins to carmalize a little, about 5 minutes. Add in garlic and saute 30 seconds longer. Stir in water, diced tomatoes, cooked quinoa, chili powder, cumin, paprika, cayenne, coriander and season with salt and pepper to taste. Bring mixture to a boil, then reduce heat, cover saucepan with lid and simmer about 15 minutes, until water has evaporated.