Step 1: Season the chicken breasts with 1 tablespoon olive oil, oregano, garlic powder, salt, and pepper.
Step 2: Cook quinoa by combining rinsed quinoa and chicken broth (or water) in a medium saucepan. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes, or until all liquid is absorbed. Fluff with a fork.
Step 3: While quinoa cooks, heat a large non-stick skillet or grill pan over medium-high heat. Cook chicken for 6-8 minutes per side, or until internal temperature reaches 165°F (74°C). Remove from heat and let rest for 5 minutes before slicing.
Step 4: Prepare the dressing: In a small bowl, whisk together extra virgin olive oil, lemon juice, dill, Dijon mustard, salt, and pepper until well combined.
Step 5: Assemble the bowls: Divide the cooked quinoa among 4 bowls. Top with sliced chicken, chopped cucumber, tomatoes, Kalamata olives, and crumbled feta (if using).
Step 6: Drizzle generously with the lemon-herb dressing and garnish with fresh parsley. Serve immediately.