Prepare the Chicken: Place the chicken breasts between two pieces of baking parchment or in a large plastic bag. Using a rolling pin or meat mallet, gently pound them to an even thickness of about 2cm. This is the key to a juicy, evenly cooked result.

Make the Marinade: In a medium bowl, whisk together the extra virgin olive oil, lemon juice, lemon zest, minced garlic, dried oregano, salt, pepper, chopped parsley, and optional red pepper flakes.

Marinate the Chicken: Place the pounded chicken breasts in a shallow dish or a large resealable bag. Pour over the marinade, making sure to coat each piece thoroughly. I find that using my hands to rub the marinade in works best. Cover the dish or seal the bag and place it in the refrigerator to marinate for at least 30 minutes, and up to 4 hours.

Preheat the Grill: When you're ready to cook, preheat your gas grill or barbecue to a medium-high heat, around 200-220°C. If using a griddle pan on the hob, heat it over a medium-high heat. Clean the grates and lightly oil them to prevent sticking.

Grill the Chicken: Remove the chicken from the marinade, allowing any excess to drip off. Place the chicken breasts on the hot grill. Cook for 6-8 minutes on the first side, until you have well-defined grill marks and the chicken releases easily from the grate.

Flip and Finish Cooking: Flip the chicken and cook for another 6-8 minutes on the second side. The chicken is cooked when it's opaque all the way through and an instant-read thermometer inserted into the thickest part registers 74°C. The UK's Food Standards Agency provides excellent guidance on cooking chicken safely.

Rest the Chicken: This is a non-negotiable step! Transfer the grilled chicken to a clean cutting board and let it rest for 5-10 minutes. This allows the juices to redistribute throughout the meat, ensuring it stays succulent.

Serve: After resting, slice the chicken against the grain and serve immediately.