Begin by dicing the chicken breast into bite-sized pieces and placing them in a mixing bowl. Drizzle with olive oil and sprinkle in dried oregano, garlic powder, onion powder, salt, and pepper. Toss together until thoroughly coated and let marinate for 10-15 minutes.

Heat a large skillet over medium-high heat, add the marinated chicken, and cook for 5-7 minutes until golden brown and cooked through (internal temperature of 165°F). Remove from skillet and set aside.

Prepare quinoa or rice according to package instructions, typically taking about 15 minutes for quinoa and 20 minutes for rice. Keep warm after fluffing the grains.

While the grains cook, chop cherry tomatoes, dice cucumber, and thinly slice red onion.

Divide cooked quinoa or rice among serving bowls. Top each with cooked chicken, chopped tomatoes, cucumber, sliced onion, crumbled feta, and Kalamata olives.

Spoon tzatziki sauce over each bowl and garnish with freshly chopped parsley. Serve immediately.