Rinse the quinoa thoroughly in a fine-mesh strainer, then combine with 0.5 cup of water in a small pot. Bring to a boil, then cover, reduce heat to low, and simmer for 12-15 minutes until water is absorbed.
While quinoa cooks, season the chicken breast on both sides with the dried oregano, garlic powder, sea salt, and black pepper.
Heat the olive oil in a medium skillet over medium-high heat. Once hot, add the chicken breast and sear for 5-7 minutes per side, or until the internal temperature reaches 165°F.
Remove the chicken from the pan and let it rest for 3 minutes before slicing into strips.
In the same skillet, add the broccoli florets and chopped red bell pepper with a tablespoon of water. Cover with a lid for 2 minutes to steam-sauté until tender-crisp.
Fluff the cooked quinoa with a fork and stir in the fresh lemon juice.
Plate the lemon quinoa, top with the sliced chicken and sautéed vegetables, and serve immediately.