Preheat oven to 375F.

Cook quinoa: Bring pot of water to a boil, add quinoa, and then lower heat to simmer. Cover, and cook until soft and liquid is absorbed, about 15 minutes.

Heat a large nonstick skillet over med-high heat. Add oil and sauté onion until lightly browned, about 5 minutes. Add garlic and sauté for 1 min. Add rest of the vegetables and combine well. Add tomato paste. Add chicken. Transfer mixture to a medium bowl and stir in quinoa and beans.

Add salsa and water to the same pan, bring to a boil, then reduce heat, and simmer for 5 minutes, stirring occasionally. Combine to the mixture.

Pour the mixture into a 9 inch by 13 inch baking dish coated with cooking spray. Sprinkle with cheese. Bake for 15-20 minutes, until cheese is melted and bubbly.

Serve with cilantro, sour cream, guacamole, etc.