Step 1: Prepare the Marinade: In a medium bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, oregano, salt, and black pepper. Mix well to combine.
Step 2: Marinate the Chicken: Pat the chicken breasts dry with paper towels. If chicken breasts are very thick, pound them lightly to an even 3/4-inch thickness. Place chicken in a resealable plastic bag or shallow dish and pour the marinade over it. Ensure chicken is fully coated. Marinate in the refrigerator for at least 30 minutes, or up to 4 hours for best flavor. Do not marinate longer than 6 hours.
Step 3: Preheat the Grill: Preheat your outdoor grill or indoor grill pan to medium-high heat (about 400°F / 200°C). Lightly oil the grill grates to prevent sticking.
Step 4: Grill the Chicken: Remove chicken from the marinade, discarding any remaining marinade. Place chicken breasts on the hot grill. Grill for 5-7 minutes per side, or until internal temperature reaches 160°F (71°C) for chicken breasts when checked with a meat thermometer. Cook time may vary based on chicken thickness and grill temperature.
Step 5: Rest the Chicken: Once cooked, transfer the grilled chicken to a clean cutting board. Tent loosely with foil and let it rest for 5-10 minutes. This allows the juices to redistribute, keeping the chicken tender and moist.
Step 6: Serve: Slice the chicken if desired, garnish with fresh parsley or cilantro, and serve immediately with fresh lemon wedges for an extra burst of citrus flavor.