Heat the olive oil in a large deep skillet over medium heat.

Add the chopped onion and minced garlic and sauté for 3 to 5 minutes until the onion is translucent and fragrant.

Push the onion and garlic to the edges of the skillet and add the chicken pieces in a single layer.

Season the chicken with the salt and black pepper and cook for 2 to 3 minutes without stirring to sear, then cook, stirring occasionally, until the chicken is no longer pink on the outside.

Stir in the rinsed quinoa, coating it in the pan juices.

Pour in the chicken broth, stir, and bring the mixture to a gentle simmer.

Arrange the broccoli florets and sliced bell peppers evenly over the top of the quinoa and chicken.

Cover the skillet with a lid, reduce the heat to low or medium-low, and cook for 15 minutes until most of the liquid is absorbed and the quinoa is tender.

Uncover the skillet, add the spinach, dried herbs, and lemon juice, and gently fold everything together.

Cover again and cook for 3 to 5 minutes until the spinach is wilted and the chicken is cooked through.

Remove from the heat, taste, and adjust seasoning with additional salt, pepper, or lemon juice if needed before serving.