Season the chicken breast evenly on both sides with sea salt, black pepper, and dried oregano.
Heat 1 tsp of olive oil in a medium skillet over medium-high heat until shimmering.
Add the chicken to the skillet and cook for 5 to 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 thin strips.
Prepare the bowl by placing the fresh spinach at the bottom and topping it with the cooked quinoa.
Arrange the halved cherry tomatoes, diced cucumber, minced red onion, and Kalamata olives over the quinoa.
Place the sliced chicken on top of the vegetable and grain mixture.
In a small jar or bowl, whisk together the extra virgin olive oil and lemon juice, then drizzle it over the entire bowl.
Garnish with crumbled feta cheese and serve immediately.