Begin by marinating the chicken breasts. In a bowl, mix olive oil, lemon juice, dried oregano, salt, and pepper. Add the chicken, making sure each piece is well-coated in the marinade. Allow it to marinate for at least 15 minutes.

While the chicken marinates, prepare your quinoa or rice according to package instructions. Fluff with a fork when done and set aside.

Heat a grill pan or outdoor grill to medium heat. Add the marinated chicken and cook for about 6-7 minutes per side, or until the internal temperature reaches 165°F (75°C). Once cooked, remove from heat and let rest before slicing.

While the chicken rests, chop your cherry tomatoes, cucumber, and red onion. Prepare the kalamata olives and crumble the feta cheese.

In a large bowl or individual serving bowls, add a generous scoop of quinoa or rice as the base. Slice the grilled chicken and layer it on top. Add the cherry tomatoes, cucumber, red onion, olives, and feta cheese.

Finish it off by drizzling a little more olive oil and some fresh lemon juice on top, if desired. Serve immediately, and enjoy!