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.
Calories 253; Total fat 6g; Saturated fat 1g; Sodium 454 mg; Total carbohydrates 37g; Fiber 7g; Sugar 3g; Protein 22g