Slice the yellow onion and red bell pepper into thin, even strips.
Cut the chicken breast into 1-inch bite-sized cubes.
Heat the olive oil in a large non-stick skillet over medium-low heat.
Add the onion strips to the pan and cook for 12-15 minutes, stirring occasionally, until they are soft and deeply golden.
Add the bell peppers and minced garlic to the skillet, increasing the heat to medium.
Sauté the mixture for 5 minutes until the peppers are tender-crisp.
Add the chicken cubes to the skillet and season with sea salt, black pepper, and dried oregano.
Cook for 7-9 minutes, stirring frequently, until the chicken is browned and no longer pink in the center.
Mix the caramelized vegetables and chicken thoroughly before serving.