Start by rinsing the quinoa under cold water. In a medium saucepan, combine 1 cup of quinoa with 2 cups of chicken stock. Bring to a boil over medium-high heat, then reduce the heat to low, cover, and simmer for about 15 minutes, or until the quinoa is fluffy and the liquid is absorbed. Set aside.
While the quinoa is cooking, cut the chicken breasts into bite-sized pieces. Season them with 1 tablespoon of fajita seasoning, ensuring each piece is well coated.
In a large skillet, heat a drizzle of oil over medium heat. Once hot, add the seasoned chicken pieces and cook for about 5-7 minutes, stirring occasionally, until the chicken is cooked through and no longer pink in the center.
Once the chicken is cooked, toss in the 2 cups of frozen pepper and onion blend. Stir well and cook for an additional 5 minutes, allowing the vegetables to heat through and soften.
In a large mixing bowl, combine the cooked quinoa, sautéed chicken, and vegetable mixture. Stir in 1 cup of salsa for added flavor and moisture.
Spoon the Chicken Fajita Bowl mixture into serving bowls. Top with a dollop of sour cream, a sprinkle of shredded cheese, and a handful of chopped green onions for a fresh finish.