Creating Greek Chicken Bowls is simple if you follow these instructions:

1. Marinate the Chicken: In a large bowl, mix olive oil, lemon juice, minced garlic, oregano, salt, and pepper. Add the chicken breasts, coating them well in the marinade. Cover and refrigerate for at least 30 minutes.
2. Cook the Chicken: Preheat a grill or skillet over medium-high heat. Remove chicken from the marinade and grill for around 7–8 minutes per side until cooked through and juices run clear. Use a meat thermometer to ensure it reaches 165°F (75°C).
3. Prepare the Base: While the chicken is cooking, cook quinoa or rice according to package instructions and set aside.
4. Chop the Vegetables: Dice the tomatoes, cucumber, red onion, and bell pepper. Place them into a large mixing bowl.
5. Combine the Ingredients: To the vegetables, add the cooked quinoa or rice, crumbled feta, and olives. Toss gently to combine.
6. Slice the Chicken: Once chicken is cooked and rested for a few minutes, slice it into strips.
7. Assemble the Bowls: In serving bowls, place a hearty portion of the quinoa or rice mixture. Top with sliced chicken and extra feta if desired. Garnish with parsley.
8. Drizzle Dressing: For added flavor, drizzle extra olive oil or a yogurt-based dressing over the top before serving, if you wish.

Following these steps will lead you to a magnificent plate of Greek Chicken Bowls that will highlight the essence of Mediterranean cuisine.