"Quinoa is a tasty, protein-filled grain that makes a great addition to chicken soup! Add some carrots, celery, spinach, onions and bell peppers for amazing color and flavor. My husband loves this with multigrain crackers, but I think it's great as-is!"
Bring 3 cups water and quinoa to a boil in a saucepan. Reduce heat to medium-low, cover, and simmer until quinoa is tender, 15 to 20 minutes.
Heat 1 teaspoon olive oil in a Dutch oven over medium-high heat. Add chicken; season with salt and pepper. Cook and stir until chicken is no longer pink in the center, about 5 minutes. Transfer chicken to a plate.
Heat remaining 1 teaspoon olive oil in the Dutch oven over medium heat. Add onion, carrots, celery, red bell pepper, yellow bell pepper, and garlic; cook and stir until soft, about 10 minutes.
Pour chicken broth into the Dutch oven. Add spinach leaves, marjoram, oregano, basil, and bay leaf. Bring to a boil; reduce heat and simmer until flavors combine, about 10 minutes. Stir in cooked quinoa. Return chicken to the Dutch oven; cook until heated through, about 2 minutes.
Dissolve cornstarch in 1/4 cup cold water in a small bowl. Pour slowly into the Dutch oven; cook, stirring occasionally, until soup thickens, about 1 minute.