Pat the chicken breasts dry with paper towels, then gently pound to an even thickness of about 1.5 cm (0.6 inches) to ensure uniform cooking.
In a small bowl, whisk together lemon juice, olive oil, minced garlic, chopped thyme, chopped parsley, salt, and black pepper to create your marinade.
Place the chicken breasts in a shallow dish and pour the marinade over them, making sure each piece is well coated. Let sit at room temperature for 15 minutes to absorb the flavors.
Preheat your grill to high heat, aiming for about 230°C (450°F), until the surface is shimmering and hot to the touch.
Remove the chicken from the marinade, letting excess drip off, then place the breasts on the hot grill, presentation side down first.
Grill for 4-5 minutes without moving, until you see deep grill marks and the edges start to firm up with a slight char.
Flip the chicken using tongs and cook for another 4-5 minutes, ensuring a good sear and even cooking on both sides.
Check the internal temperature with a meat thermometer; the chicken should reach 74°C (165°F). The juices should run clear when pierced, and the meat should feel firm but not hard.
If needed, move the chicken to a cooler part of the grill, cover, and cook for another minute to reach perfect doneness.
Transfer the cooked chicken to a plate and let rest for 5 minutes, loosely tented with foil, to allow the juices to redistribute and keep it moist.
Slice the chicken against the grain, then serve immediately, enjoying the juicy interior with a beautifully charred exterior, enhanced by the bright citrus herbs.
